A generation ago, the graduating class at Manchester High School was 300 students. This year, it is 18% larger. What is the current size of the graduating class?

1 Answer
Jan 13, 2017

Answer:

The size of the current graduating class is 354.

Explanation:

The formula for determining the rate of change is:

#p = (N - O)/O * 100#

Where:

#p# is the percentage of change - 18 in this case.
#N# is the New Value - what we are solving for
#O# is the Old Value - 300 for this problem.

Substituting and solving for #N# gives:

#18 = (N - 300)/300 * 100#

#18 = (N - 300)/(3 * 100) * 100#

#18 = (N - 300)/(3 * color(red)(cancel(color(black)(100)))) * color(red)(cancel(color(black)(100)))#

#18 = (N - 300)/3#

#18 * color(red)(3) = (N - 300)/3 * color(red)(3)#

#54 = (N - 300)/color(red)(cancel(color(black)(3))) * cancel(color(red)(3))#

#54 = N - 300#

#54 + color(red)(300) = N - 300 + color(red)(300)#

#354 = N - 0#

#354 = N#

#N = 354#