Question

The mean preparation fee H&R Block charged retail customers in 2011 was $183 (The Wall Street Journal, March 7, 2012). Use this price as the population mean and assume the population standard deviation of preparation fees is $45.

1. Suppose you have a sample of 55 customers. What is the expected value and standard error of x?
2. Calculate the probability that the mean price for a sample of 300 H&R Block retail customers is within $12 of the population mean (i.e. +/- 12) .Confirm your answer with this R code.

# pnorm outputs P(x<c) for normal distribution

# Probability of selecting a random sample with a sample mean

# within $12 of the population mean; using a sample size of n = 55

pnorm(195, mean = 183, sd = 45/sqrt(55)) - pnorm(171, mean = 183, sd = 45/sqrt(55))

hello, thanks for helping

i know i should post one question at a time, but i posted two since Q1 and Q2 are interconnected.

The R part confuses me.

Answer 1