The Postmaster at the Harrington Post Office would like to compare the delivery times to two different locations which are the same number of miles from Harrington. A random sample of letters are to be divided into two equal groups, the first delivered to Location A and the second delivered to Location B. Each letter will be delivered on a randomly selected day and the number of days for each letter to arrive at its destination is recorded. The measurements for both groups are expected to have a range (variability) of approximately 4 days. If the estimate of the difference in mean delivery times is desired to be correct to within 1 day with probability equal to 0.99, how many letters must be included in each group? Assume n₁ = n₂ = n.
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The Answer of The Postmaster at the Harrington Post Office would like to compare the delivery times to two different locations which are the same number of miles from Harrington. A random sample of letters are to be divided into two equal groups, the first delivered to Location A and the second delivered to Location B. Each letter will be delivered on a randomly selected day and the number of days for each letter to arrive at its destination is recorded. The measurements for both groups are expected to have a range (variability) of approximately 4 days. If the estimate of the difference in mean delivery times is desired to be correct to within 1 day with probability equal to 0.99, how many letters must be included in each group? Assume n₁ = n₂ = n. ______________

The Postmaster at the Harrington Post Office Would Like to Compare