Melody

@@ What is Happening?  [Wrap4]   Sun 29/11/15   Sydney, Australia Time 9:30 pm   ♪ ♫

A very good day to you all,     

We have had wonderful answers from CPhill, Alan, Heureka, geno3141, Dancer04, Annonymous4338, buubleman, Dragonlance, DragonSlayer554, TitaniumRome, Riddles, Olivia3.141592654, Acer32 and Mattesnillet.  

WOW that is a lot of answerers.  Thank you everyone   

Social report       

I think this must be ther return of the old members week!  Is that because December is nearly upon us?  Lets see, Anonymous4338 has been back for a week or so, DragonSlayer554 returned yesterday, TitaniumRome made his presence felt today.  You three, along with Riddles, Olivia4.14... and Hayley if she is still with us could try and boost the young crowds interest with riddles, puzzles, and quality social threads.  Along with your standard questions and answers of course.

Also Dbg4thebest has posted a new Music report.  I would really like members and guests to support him please.  Thanks Denzel     The post is with the interest posts below. :)

Forum Issues:

There was a problem with posting pictures today.  If this is still a problem tomorrow I intend to send a note off to admin :)

Interest Posts:

If you ask or answer an interesting question, you can private message the address to me (with copy and paste) and I will include it.  Of course only members are able to do this.  I quite likely will not see it if you do not show me.  

1) Music Report #10      Thanks Dbg4thebest       

Yes, thank you very much Alan :)

I think yours was faily intuitive to someone with a lot of maths training. Perhaps you could have said a little more for the extended audience, maybe I could have too, but I think your answer was good.   If anyone askes you or me to explain our answers I know we will be more that happy to oblige. I expect our guests would be happy to oblige too :D

I like the method that you used the best. :)  It was really simple.  :)

We cannot post pics today.  :((

Observations from 

Dragonslayer, CPhill, Alan and myself.

https://web2.0calc.com/questions/system-problem#r5

Thanks Danzel,

I have had a great music day today and I really enjoyed your contributions to it.

I especially liked this one:

Varien- nights in bangalore pt. 2

https://www.youtube.com/watch?v=Jv1E1jYVt2s

I found the instrumentation and voice combination very interesting !

 I would like to seee this performed and get close ups of what is going on.

Do you know if such a clip would exist?

Thank you very much for contributing and for adding to the general appeal of our 'maths' forum   

I like your answer Chris.  Guest 1 and 2 gave good answers too :)

It is a bit unclear what intuitive means to this student or their teacher.

We have all used some algebra.

I took intuitive to mean that we needed to explain the algebra that we were using.  

I think CPhill and guest 2 interpreted it the same way.  :)

A class average mark in an exam is 70. The average of students who scored below 60 is 50. The average of students who scored 60 or more is 75. If the total number of students in this class is 20, how many students scored below 60?

20 in class

mark average is 70

average below 60 is 50

the average of 60 or more is 75

I am going to split the class into 2 groups.  Those who got below 60 (Lower)  and those who got 60 or more.(Upper)

I do no know how many are in each group but I do know that there are 20 students altogether so the lower+upper  =20

The average of the lower marks is  50      so   sum of lower marks  is 50L

The average of the upper marks is  is  75      so   sum of upper marks  is 75U

Now there are 20 students and the average mark is 70

so     (50L+75U)/20   =70

50L+75U   =70*20

2L+3U=(70*20)/25

2L+2U+U=56

But 2L +2U=2* all the students = 40

40+U=56

U=16

There are 16 studens in the top group so there must be 4 students in the top group.

Answer: 4 students scored below 60. 

Thanks Dragonlance, the last bit confused me.  I'll think about your answer  :)

5.    The probabilities for Elizabeth and Edward to choose Business as their major are 0.8 and 0.3, respectively. 

Find the probability that:

a).    Both choose Business as their major.

P = ( both choose Business as their major ) = (0.8) . ( 0.3) = 0.24    yes

b).     Neither chooses Business as their major.

P = ( Neither chooses Business as their major ) = (0.2) . ( 0.7) = 0.14    yes

c).    Only Elizabeth chooses Business as her major.    

          = ( This means Elizabeth does Business and Edward does NOT do business) = 0.8*0.7 = 0.56

So our guest#1  was totally correct!

Hi Buubleman :)

Draw a right angled triange.

put theta in one of the acute angles.

cos theta = 5/13

So adjacent side is 5 and the hypotenuse is 13

Us pythagotean theorum to find the opposite side and it is 12

now you should be able find all the rations and put them together as you hve been asked :)