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A random sample of 25 observations has been drawn from a normal distribution with mean 45 and standard deviation 10. Find the probability that the sample mean is in the interval 40 ≤ x ≤ 50 .   Round your answer to 4 decimal places.

A normal population has mean 100 and variance 25. How large must the random sample be if you want the standard error of the sample average to be 1.8? Round your answer to an integer.

The time between service requests to an electrical repair shop is exponentially distributed with a mean time of 20 minutes.Find the probability that no requests arrive within a 30-minute interval.Round your answer to 4 decimal places.

The time between customer arrivals at a car wash is exponentially distributed with a mean of 10 minutes.What is the probability that there are no customers within a 25-minute interval?Round your answer to 4 decimal places.

A normal population has mean 100  and variance 25. How large must the random sample be if you want the standard error of the sample average to be 1.5? Round your answer to an integer

Determine the value of k such that the function f(x,y) = kx2y for 0

For a probability density function f(x)=1−x2 for the range −1 < x < 1 and 0 elsewhere, what is the lower limit [A] and what is the upper limit [B] for P( 0.3 < x < 1.5)?

Find P(x = 75 , y

Find P(x < 50 , y = 75) using the joint Probability distribution table given below

By how much must the sample size n be increased if the length (width) of the CI is to be halved? For example – if it increased by 2 times then your answer should be “2”