Question

Erica can thoroughly analyze the company’s monthly credit card statements
in 80 minutes. It takes Alexa 2 hours to do the same job. One afternoon, Erica and Alexa start analyzing the company’s credit card statements together. Half an hour later, Mack, the new employee, joins them. If the three of them finish 15 minutes later, how long would it have taken
Mack to analyze the company’s monthly credit card statements on his own?

Answer 1

Answer:

240 minutes or 4 hours

Step-by-step explanation:

So if it takes Erica 80 minutes to analyze the company's monthly credit card statements, she will get 30/80 of it done in 30 minutes.

If it takes Alexa 2 hours to analyze the company's monthly credit card statements, she will get 30/120 of it done in 30 minutes.

Add 15 to each of the fractions because they analyze the company's monthly credit card statements with Mack for 15 more minutes.

So you have 45/80 and 45/120.

Now add both fractions by finding the lowest common denominator which is 240.

135/240 + 90/240 = 225/240

So Mack did the remaining 15/240.

Now to find how long it would take him to analyze the company's monthly credit card statements by himself divide 240 by 15 which is 16.

Then multiply

15 x 16 = 240

so it would take him 240 minutes or 2 hours.