Because sample means were being tested, the is used to calculate the z-score

Formula to calculate Z score

Where,   a=Population mean

b=Sample Mean

c=Standard Deviation of the sample

Because sample means were being tested, "The Sample Standard Deviation and Population Mean" is used to calculate the z-score

answer:   28.56 feet (approx)

step-by-step explanation:

since, triangle abc has measure of angle c equal to 55 degrees, measure of angle abc equal to 90 degrees, and length of bc equal to 20 feet.

we have to find out the measurement of segment ab.

therefore, tan 55° =

but bc = 20 feet.

⇒ tan 55 ° =  

⇒ ab = 20 × tan 55 °

⇒ ab = 20 × 1.42814800674

⇒ ab = 28.5629601348   ≈ 28.56 feet