You need to estimate how much money dog owners spend on their pets on average per month. You wish to express your estimate as a 90% confidence interval whose width does not exceed 5 euros. Previous...

You need to estimate how much money dog owners spend on their pets on average per month. You wish to express your estimate as a 90% confidence interval whose width does not exceed 5 euros. Previous studies indicate that the standard deviation is approximately equal to 84 euros, and therefore you decide to use this value as an estimate of the population standard deviation.

At least how many dog owners will you need to include in your sample? Round the result up to the nearest integer.