Question

indicated place values. 2) According to Moebs Services Inc., an individual checking account at major U.S. banks costs the banks between $350 and $450 per year. A recent random sample of 600 such checking accounts produced a mean annual cost of $500 to major U.S. banks. Assume that the standard deviation of annual costs to major U.S. banks of all such checking accounts is $40. Make a 99% confidence interval for the current mean annual cost to major U.S. banks of all such checking accounts. (10 points total) Step 1: Determine the critical value. (1 point) Step 2: Calculate the Margin of Error. Round to two decimal places. (3 points) Step 3: Calculate the Confidence Interval as an interval. Round to two decimal places. (4 points) Step 4: Write an interpretation. (2 points) 3) Using the standard deviation from number (2), how many such checking accounts would need to be studied for a 98% confidence, with a margin of error of $1.25? (5 points)

PLEASE DO # 3

Answer 1

The following information is provided,
Significance Level, α = 0.02, Margin or Error, E = 1.25, σ = 40

The critical value for significance level, α = 0.02 is 2.33.

The following formula is used to compute the minimum sample size required to estimate the population mean μ within the required margin of error:
n >= (zc *σ/E)^2
n = (2.33 * 40/1.25)^2
n = 5559.19

Therefore, the sample size needed to satisfy the condition n >= 5559.19 and it must be an integer number, we conclude that the minimum required sample size is n = 5560
Ans : Sample size, n = 5560