When testing a null hypothesis about a single population mean and the population standard deviation is unknown, if the sample size is less than 30, one compares the computed test statistic for significance with a value from the distribution.

t-distribution

Step-by-step explanation:

When sample size is less than 30, t-distribution is used

When sample size is greater than 30, z-distribution is used

8(-10x+3.5y-7)

8×-10x + 8×3.5y + 8×-7

-80x + 28y - 56

therefore

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

chicken chicken chicken

step-by-step explanation: