Question

Six football players, all defensive linemen, decide that they'll gain an average of 10 pounds over the summer. At the start of the season, only five showed up for the weigh-in. They had gained 9, 13, 11, 6, and 7 pounds. How many pounds does the last person have to gain so that the group can attain its goal?
a. 12 pounds
b. 14 pounds
c. 13 pounds
d. 14. 5 pounds

Answer 1

Answer: b. 14 pounds

Step-by-step explanation:

Formula to calculate average :

$\text{Average}=\dfrac{\text{Sum of all observations}}{\text{Number of observations}}$

Let x denotes the number of pounds the last person have to gain so that the group can attain its goal.

Required average = 10  pounds

Observations = 9, 13, 11, 6, 7 and x (pounds)

Number of observations= 6

Sum of all observations = 9+13+ 11+ 6+7+x=46+x

According to the question , we have

$10=\dfrac{46+x}{6}\\\\ 46+x=10\times6\\\\ 46+x=60\\\\ x=60-46=14$

i..e the last person has to gain 14 pounds so that the group can attain its goal.

Hence, the correct answer is b. 14 pounds .