The grades of a science test are normally distributed. Thanh finds that his grade on the test has a z-score of â€""2. 5. Which statement must be true? Thanh’s grade is 2. 5 standard deviations below the mean of the test grades. Thanh’s grade is 2. 5 points below the mean of the test grades. Thanh’s grade is 2. 5 standard deviations above the mean of the test grades. Thanh’s grade is 2. 5 points above the mean of the test grades.

step-by-step explanation:

answer: about 22.67

step-by-step explanation:

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