A teacher gave a unit test to both of her statistics classes. The mean test grade for Class A was 77 points, with a standard dev
1 answer:
You might be interested in
Answer:
0.0903
Step-by-step explanation:
Given that :
The mean = 1450
The standard deviation = 220
sample mean = 1560
P(X> 1560) = P(Z > 0.5)
P(X> 1560) = 1 - P(Z < 0.5)
From the z tables;
P(X> 1560) = 1 - 0.6915
P(X> 1560) = 0.3085
Let consider the given number of weeks = 52
Mean = np = 52 × 0.3085 = 16.042
The standard deviation =
The standard deviation =
The standard deviation = 3.3306
Let Y be a random variable that proceeds in a binomial distribution, which denotes the number of weeks in a year that exceeds $1560.
Then;
Pr ( Y > 20) = P( z > 20)
From z tables
P(Y > 20) 0.0903