CPhill

z - 1/2 = 1/10     add 1/2 to both sides

z = 1/10  + 1/2           [1/2 =  5/10]

z = 1/10 +  5/10  

z  = 6/10   =   3/5

Same to you.......penquino  !!

Using  

s = rθ        s = arc lengh   r = radius    θ is in rads

6 = 5θ  

6/5  rads  = θ 

Converting rads to degrees, we have :

(6/5) *180 / pi  ≈  68.8°   [rounded]

To be honest, EP.....I'm not that great at those two areas, either......I learned a lot from Melody and Alan....!!!

P.S. .......  I like Omi's "tree−diagram" approach, too.....!!!!

total amount  =  15 + 2.50x     where x is the number of rolls of film  developed....so we have.....

15  + 2.50 (5)   = $27.50

P (two whie)  =  15/27 * 14/26  =   35/117

P(two black)  =  12/27 * 11/26  =    22/117

So....the total probability  =  [35 + 22]  / 117   =   57/117  = 19/39  ≈  48.7 %

Just as EP found.....!!!

P (two whie)  =  15/27 * 14/26  =   35/117

P(two black)  =  12/27 * 11/26  =    22/117

So....the total probability  =  [35 + 22]  / 117   =   57/117  = 19/39  ≈  48.7 %

3 - 3 x 6 + 2 =

3 - 18  + 2  =

-15  + 2  =

-13

Verified here :

http://www.wolframalpha.com/input/?i=3+-+3+x+6+%2B+2

Find  the answer to (c)  here :   https://en.wikipedia.org/wiki/Poker_probability

Here's (a)  :

a)  We choose  three of the four fives = 4 ways to do this ....  and two of the four tens = 6 ways to do this

This makes 4 x 6   = 24  such hands.......and there are  C(52,5)  = 2,598,960 possible hands....so the probability is   : 24 / 2,598,960  = 1/108,290