The probability of finding 2 never married
10c2*0.4^2*0.6^8=
the probability of finding 1 never married
10C1*0.4*0.6^9=
the probability of finding 0 never married
10C0*0.6^10=
the answer is all the above answers added together.
think you can do the rest of the calculation by yourself. :)
btw nCr=n!/(n-r)!r!
good luck
Edit to reflect comments:
3^-1=1/3
4^-1=1/4
Flip the fraction over basically i.e. 4/1---->1/4
A single drink would cost be $1.55. This is because:
13 + 4x - 6 = 13.20.
(13.20 - 13 + 6) = 6.20.
6.20 / 4 = 1.55
Hope this helped.
ANSWER
C. 64.29
EXPLANATION
The bigger right triangle is similar to the smaller right triangle, therefore

Multiply both sides by 30;

Simplify


We correct to the nearest hundredthth to obtain,

The correct choice is C.
When calculating probability you need to remember that probability is:
something that you are observing divided by total number of participants.
The number you get is relative value(has value between 0 and 1) and if you want to get it in percentage (more clearly) just multiply it with 100.
In this case we are observing blood type B persons. Number of them is 165.
Total number of persons is 1500. Therefore our calculation looks like this:
165/1500 = 0.11 or the probability is 0.11*100=11%