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+118725

Guest:
the hypotenuse of a right triangle measure 9 inches and one of the acute angles measure 36 degress. what is the area of the triangle rounded to the nearest tenth

You could find the adjacent side using trig and then use A = 1/2 absinC

Or you could find both the adj and the opp sides using trig and then use A = 1/2 ab

MelodyFeb 18, 2014

+118725

Guest:
80% of what number is 60?

80% of x = 60

0.80x = 60

divide both sides by 0.80

MelodyFeb 18, 2014

+118725

jonathan:
9/16+2/8

Chang it to 9/16 + 4/16 then add the tops and leave the bottom as 16.

MelodyFeb 18, 2014

+118725

lol:
A4273B is 6 digit no. in which A and B are digits and the no. is divisible by 72. Find A and B

If the number is advisable by 72, it must be dividable by all the factors of 72
So it will be divisable by 2,3,4,6,8,9,12,18,24, and 36

If you don't know how to check for these you could look here. We did this at length recently.

http://web2.0calc.com/questions/viewtopic.php?f=2&t=7778&hilit=divisibility

Highlight, right click and choose goto

MelodyFeb 18, 2014

gueghehguheufuebfuebyrfueufyebienurb rbrugb rugbru b urbgur grubgurbgrbgurh8huebgibrufbubvuvburbugfiheifbbvjr rnhr rv r r u u hv rjrbu r ur hg h b rb fb b b rubwibfjrbjr hrbe b ubrhbbdtburbbr fuhhrihirhieheihriheirhirffn ubruburfurububg fueuhufirnfubgh bf fhbr rbr uwbue uf vubfub e fubvurbfimuu dufbrububfrufbj vub fef f ufb feuelly help with m

help with my homework a fence runs across a steep hillside.The fence is tilted downhill and forms a curve rather than a straight line.What do you think happened?y piece bfeufiibdibefebje i need r

GuestFeb 18, 2014

a fence runs across a steep hillside.The fence is tilted downhill and forms a curve rather than a straight line.What do you think happened?

GuestFeb 18, 2014

y=1x-1

GuestFeb 18, 2014

Quote:
what is 1.0841 estimated

Looks to be about 1 to me.

Gabby the counting mule says 1 too.

GuestFeb 18, 2014

An easy thing to do is list the multiples of 8 and 7:

So, for starting off: 8: 8, 16,24,32, and so on. Try listing multiples until you find a common number.

OR

You can multiply 8 and 7.

Hope this helps!
JyotiG

GuestFeb 18, 2014

Feb 17, 2014

+118725

MileyT:
:?: 1.8e20/6.022e23

Why can't you do this yourself
There is a calculator on the site.

MelodyFeb 17, 2014

+118725

PROBLEM #1.
You have sampled a population in which you know that the percentage of the homozygous recessive genotype (aa) is 36%. Using that 36%, calculate the following:
The frequency refers to the frequency in the population.

The frequency of the "aa" genotype.
The frequency of the "a" allele.
The frequency of the "A" allele.
The frequencies of the genotypes "AA" and "Aa."

Hi tjhill19,
I see that you have become a member. Welcome to Web2.0calc forum.
Your questions are interesting. I shall have some fun trying to help you.

I am not a biologist so I may not use the correct words or put them together in the correct ways. Sorry about that.
Now, these are probability questions. They are Bernoulli probability questions that use binomial techniques to solve. (Once again my words may not be quite correct, I have always just referred to them as binomial probability questions.)
Now.
Each strand of DNA is a double helix. I have not heard the word allele before but it must be the the gene on one side of the double helix.
This means that for any particular genotype (on just one side of the double helix) you either have a recessive a allele or you have the Dominant A allele.
You have one or the other, you can't have both, and you can't have anything else.
Since it is a double helix, these are the combinations that are possible
AA
Aa
aA
aa

Now I need to discuss probability.
All probabilities must be between 0 and 1
If the event cannot happen then the probability is 0
if the event is absolutely going to happen then the probability is 1
The probability of an event happening = the number of ways it can happen / the total number of things that can happen altogether.

"You have sampled a population in which you know that the percentage of the homozygous recessive genotype (aa) is 36%. Using that 36%, calculate the following:"
If the genotype is homozygous it means that both sides of the double helix carry the same gene (One was inherited from the mother and the other from the father)
They are both the recessive gene which means that this trait (whatever it is) will tend to be unusual in the population. If only one was a and the other was A then the alternate trait would be the one in evidence.

Back to probability
say i have 7 b***s in a bag. 3 are blue and 4 are red
If i choose a ball at random then the probability that it will be blue is 3/7 the probability that it will not be blue is 4/7 (3/7 + 4/7 = 1 this must be so because I have to choose one or the other.)
This is a large part of what makes it a binomial probability. Either one thing happens or it doesn't. Nothing else is important.
If I put the ball back into the bag and choose again then on the second try
The probability that it will be blue is 3/7 the probability that it will not be blue is 4/7 (Exactly the same as before)
This is another large part of what makes it a binomial probability. Each trial is independent of all other trials, the odds (probability) of success stays the same.

Now the probability of selecting two Blue b***s is P(BB) = 3/7 * 3/7 = 9/47 (it is always multiply for questions like these)

Going backwards now, (I know that there are only blue and red b***s to choose from)
if i was told that the probability of choosing 2 blue b***s was 9/47 . I could know from that. that the probability of choosing a blue ball on a single trial must be sqrt( 9/49) = 3/7
If the probability of choosing a blue ball is 3/7 then the probability of NOT choosing a blue ball must be 1- 3/7 = 4/7
The probability of choosing 2 NON blue b***s must be 4/7 * 4/7 = 16/49
Since it is blue b***s that I want I am going to let the probability of choosing a blue be 'p'
and I am going to let the probability of not choosing a blue by 'q'
p+q = 1 ==> or alternatively q=1-p
also if I square both sides
(p+q) ² = 1 ²
(p+q) ² = 1
p ² + 2pq + q ² = 1 (these were the formulas you were told that you must learn, but it would be better if you understood them rather than just memorized them)
If you don't understand how i did this expansion - make sure you ask and i will show you.

Back to your question
You have sampled a population in which you know that the percentage of the homozygous recessive genotype (aa) is 36%. Using that 36%, calculate the following:
The frequency refers to the frequency in the population.

The frequency of the "aa" genotype. 36% It is in the question ===> p ² from the formula
The frequency of the "a" allele. sqrt(36%)= sqrt(0.36) or 0.6 ==> 60%
The frequency of the "A" allele. 1-60% = 40%
The frequencies of the genotypes "AA" and "Aa."
P(AA) = 0.4 * 0.4 ==> 0.16 =======16% =====> q ² from the forula
P(Aa)+P(aA) = 2* 0.4* 0.6 = 0.48 ==> 48% ===> this is 2pq (from the formula)

The frequencies of the two possible phenotypes if "A" is completely dominant over "a."
the phenotype must be the way in which the trait presents itself in the population.
The recessive gene will only present if the homozygous recessive genotype (aa) is present
Therefore the dominant phenotype will occur 16% + 48% = 64% of the time.
Since we already knew that the recessive phenotype would occur 34% of the time.
We could also have said that the recessive phenotype would occur (100-34)% = 64% of the time.

-------------------------------------------------------------------------------------------------------------------------------

P(A) + P(a) = p+q =1
P(AA) + [P(Aa)+P(aA)] + P(aa) = p ² + 2pq + q ² = 1

Try and digest what I have said and then get back to me.
Maybe you can try the next problem by yourself.

MelodyFeb 17, 2014

1/3

GuestFeb 17, 2014

+6252

Quote:
calculate the simple interest on $4500 at 7.3% for 260 days (use the exact method).

I don't know what the "exact method" is but assuming 7.3 annual interest with no compounding you get

I = 4500 * (0.073) * (260/365) =

4500 * 0.073 * (260/365)

RomFeb 17, 2014

+6252

Quote:
A4273B is 6 digit no. in which A and B are digits and the no. is divisible by 72. Find A and B

this number is

N = 100000A + B + 42730 and

N mod 72 = 0

42730 mod 72 = 34

100000 mod 72 = 64 so

N = 64A + B + 34 = 0 (mod 72)

(64A+34) mod 72 = 72 - B

at this point I don't know anything more clever than making a small table and looking for A such that

(64A+34) mod 72 is within 9 of 72

doing this you find A=5 and B=6

542736 / 72 = 7538

RomFeb 17, 2014

Thanks. (STU)

GuestFeb 17, 2014

+6252

Quote:
what is 1/4 times 4 to the power of 3/2

there are a few ways to go about this, probably the easiest is

(1/4) 4 ^(3/2) =

(1/4) 4 ^(1+1/2) =

(1/4)(4 * 4 ^(1/2)) =

1 * 4 ^(1/2) =

4 ^(1/2) =

sqrt(4) = 2

RomFeb 17, 2014

+6252

Quote:
How to find an angle between a found magnitude vector and the x-axis

a general vector can have both any magnitude >= 0
and any angle.

So if you are just given the magnitude of a vector there's no way to calculate it's angle from the x-axis. You need more info.

RomFeb 17, 2014

+6252

as your concrete example

log ₄(78) = log ₁₀(78) / log ₁₀(4)

Now you talk about calculating these things manually. I'm not entirely sure what you mean by that. Even for base 10 logs eventually you're going to be reduced to one of 3 ways of getting the actual value

a) punching the buttons on your calculator
b) looking the value up in a table
c) approximating it by it's series or perhaps some other approximation formula

unless of course the argument is a power of the base in which case the log is just that power, for example

log ₁₀(1000) = log ₁₀(10 ³) = 3
log ₄(1024) = log ₄(4 ⁵) = 5

without using one of the methods a-c above about the best you can do is note that

4 ³ = 64 < 78 < 256 = 4 ⁴

and thus 3 < log ₄(78) < 4

back in the old days before electronic calculators (and yes I was alive back then) all we had was tables of base 10 logs and every problem involving logs first had to be converted to base 10 using the formula I gave you, and then done in base 10 and converted back if necessary. With pencil and paper (or a slide rule if you had one).

If you're interested in the series I'm referring to in (c) above you can read about it here. http://en.wikipedia.org/wiki/Logarithm#Calculation

RomFeb 17, 2014

+1313

That isn't that clear to me Rom. Also I'm unsure which part of the question you're answering specifically. Though I feel it's conversion process for any log function into a base 10 log. But it seems alien and a bit backwards, though I'm sure it's not.
Specifically, this does not expalin to me how it goes from a log 4 function to a log 10 function, or how to calculate a log 4 function manually, in steps (since I have the problems and the fomulae but not the method) and It does not really explain what is x b and c, where we have one equation, what's what.

logb(x) = logc(x) / logc(b)

so

log10(x) = logc(x) / logc(10)
If you could explain it a bit more thanks.

My interpretation would be logb is log input any base and it will be calculated by log original base by log new base. And what about powers? And how do we solve for powers? What's the step from log 2 or 4 or 7 etc.

Still would like to know the calculation method to manually calculate for example log ₄78. and maybe you can show a little bit of a more difficult log problem and solve to show me also. But I'd like to know the method of working through it specifically and where powers are involved. Ie. what's being Sqrt'ed, multiplied, divided etc to come up with an answer if any one would like to help.

StuFeb 17, 2014

+6252

Quote:
4 gallons equals how many cups?

8 oz to a cup
2 pints to a quart
4 quarts to a gallon

4 gallon = 4 gallon * 4 quart/gallon * 2 pint/quart * 8 oz/pint = 256 oz

notice how all the units cancel each other out until you're left with oz at the end.

RomFeb 17, 2014

+6252

log _b(x) = log _c(x) / log _c(b)

so

log ₁₀(x) = log _c(x) / log _c(10)

RomFeb 17, 2014

+1313

I'd neglect to answer this question based on your user name. Please register a better name or take your energy elsewhere.

StuFeb 17, 2014

+1313

6 or 6 ones or six units.

StuFeb 17, 2014

+118725

I have no idea, sorry.

MelodyFeb 17, 2014

+1313

Bump~ Title your posts well to find it again in search engine and to help others to do so as well.

StuFeb 17, 2014

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