25% said that they preferred a particular brand of shampoo, the rest is 75 %
Answer: 
Step-by-step explanation:
Given : In a sociology class there are 14 sociology majors and 11 non-sociology majors.
Total students = 14+11=25
Number of students are randomly selected = 3
Then, the number of ways to select 3 students from 25 students :-
Number of ways to select at least 2 of the 3 students re non-sociology majors :-
The probability that at least 2 of the 3 students selected are non-sociology majors will be :-
Answer:
-3 degrees C
Step-by-step explanation:
We need to subtract 3 degrees from Thursdays temperature
0 - 3
-3 degrees C
Let's call our estimate x. It will be the average of n IQ scores. Our average won't usually exactly equal the mean 97. But if we repeated averages over different sets of tests, the mean of our estimate the average would be the same as the mean of a single test,
μ = 97
Variances add, so the standard deviations add in quadrature, like the Pythagorean Theorem in n dimensions. This means the standard deviation of the average x is
σ = 17/√n
We want to be 95% certain
97 - 5 ≤ x ≤ 97 + 5
By the 68-95-99.7 rule, 95% certain means within two standard deviations. That means we're 95% sure that
μ - 2σ ≤ x ≤ μ + 2σ
Comparing to what we want, that's means we have to solve
2σ = 5
2 (17/√n) = 5
√n = 2 (17/5)
n = (34/5)² = 46.24
We better round up.
Answer: We need a sample size of 47 to be 95% certain of being within 5 points of the mean
