Question

For every 15 columns of news stories in a newspaper, 4 columns of ads are required. If a newspaper contains 300 columns of news stories, how many columns of ads must it have?

Answer 1

GIVEN: For every 15 columns of news stories there are 4 columns of adds.

If there are 300 columns of news stories, we will need to find out how many sets of 15 columns are in the newspaper. We can do this by dividing 300 by 15.

300/15 = 20

Knowing that there are 20 sets, and 4 columns of ads must be in each 20 set we can mulitply 20 by 4.

20 x 4 = 80

Final Answer: If a newspaper contains 300 columns of news stories, there must be 80 columns of ads.

Answer 2

The problem can be solved by proportion as following

For every 15 columns of news stories in a newspaper, 4 columns of ads are required

If a newspaper contains 300 columns of news stories, x columns of ads are required
∴ 15 : 4 = 300 : x
∴ $\frac{15}{4} = \frac{300}{x}$
By using cross multiplication
∴ 15 x = 4 * 300
∴ 15 x = 1,200
∴ x = 1,200/15 = 80

So, the number of columns of ads must it have = 80