Class A: 3 out of 30 = 3 / 30 = 0.1 = 10%
Class B: 28 out of 40 = 28 /40 = 0.7 = 70%
Class C: 11 out of 28 = 11 / 28 = 0.39 = 39%
Class D: 14 out of 50 = 14 / 50 = 0.28 = 28%
The answer is Class D
So will be 27 -50 - 81 +81 = - 23
hope this will help you
The equation to calculate how many ways that "r" things can be chosen from a larger set of "n" things is:n! / [r! * (n-r)!] =
12! / (5! * 7!) =
12 * 11 * 10 * 9 * 8 * 7! / (5! * 7!) =12 * 11 * 10 * 9 * 8 / 5 * 4 * 3 * 2 =11 * 9 * 8 =792 ways
http://www.1728.org/combinat.htm
THis is a binomial distribution:-
P( 3 tails) = 15C3 (0.5)^3(0.5)^12
= 0.0139
P(5 tails) = 15C5 (0.5)^5(0.5)^10
= 0.0916
P(3 or 5) = 0.0139 + 0.0916 = 0.1055 Answer
