The mean number of travel days per year for salespeople employed by hardware distributors needs to be estimated with a 0.90 degree of confidence. For a small pilot study the mean was 150 days and the standard deviation was 14 days. If the population mean is estimated within two days, how many salespeople should be sampled

133

Step-by-step explanation:

Given that :

Degree of confidence, α = 0.90 ; The Zcritical vlaue at α = 90% is 1.645

The margin of error, MOE = ±2

Standard deviation, s = 14

Using the relation :

n = (Zcritical * standard deviation) / MOE

n = ((1.645 * 14) / 2)²

n = (23.03 /2)²

n = 11.515²

n = 132.595

n = 133 samples

8(-10x+3.5y-7)

8×-10x + 8×3.5y + 8×-7

-80x + 28y - 56

therefore

-80x+28y-56 is the correct answer