If each year the average boy gains 8.2 pounds, how old will the average boy be when he weighs 124.7 pounds?

Question

The average weight for four year old boys is 34.5 pounds. If each year the average boy gains 8.2 pounds, how old will the average boy be when he weighs 124.7 pounds?

Answer 1

Hi Juice,

 

Let's begin by assigning a letter to represent our unknown:

    x = number of years to reach weight of 124.7 lbs.

 

If the starting weight is 34.5 lbs. and 8.2 lbs is the weight increase per year then we can set up this equation to solve for our unknown (x):

    34.5 + 8.2x = 124.7

 

Solving for x:

    34.5 + 8.2x = 124.7

    8.2x = 124.7 - 34.5

    8.2x = 90.2

        x = 90.2/8.2

        x = 11 (number of years to reach weight of

                   124.7 lbs.)

 

Now to calculate the age at which an average boy will reach weight of 124.7 lbs., we must add the age of the average boy (4 years) at the starting weight (34.5 lbs.) to the number of years it takes to reach weight of 124.7 lbs:

    11 + 4 = 15 (age of average boy at weight of

                           124.7 lbs)

 

 

Thanks for submitting this problem and glad to help.

 

God bless, Jordan.