Question

Twenty-two people have hair 2.5 inches long and twenty-eight people have hair 5.7 inches long. What is the average hair length of all the people detailed? A. 4.29 B. 5.10 C. 4.92 D. 4.57​

Answer 1

A. 4.29

Explanation:

The average of a set of numbers is the sum of the numbers divided by the total numbers present.

Sum of numbers: Instead of having to write out 2.5 twenty-two times and 5.7 twenty-eight times, we can remember that adding 2.5 twenty-two times is the same as multiplying 2.5 and 22 while adding 5.7 twenty-eight times is the same as multiplying 5.7 and 28. Thus, our numerator for the average is (2.5 * 22) + (5.7 * 28)

Total number of people: We know that there are 50 people in all since 22 + 28 = 50. Thus, our denominator for the average is 50

Average: We divide our numerator by our denominator and simplify to find our average:

Average = ((2.5 * 22 + (5.7 * 28)) / 50

Average = (55 + 159.6) / 50

Average = 214.6 / 50

Average = 4.292

Average = 4.29

Thus, the average and our answer is A. 4.29