For 12 days, Keisha keeps track of how much water she drinks per day. 1 1/2 quarts, 2 1/4 quarts, 2 quarts, 1 1/2 quarts, 1 3/4 quarts, 1 1/2 quarts, 1 1/4 quarts, 2 quarts, 2 1/4 quarts, 1 1/2 quarts, 2 quarts, 1 1/2 quarts. What is the total amount of water that Keisha drinks the 12 days? Please show work. I know the answer is 21, but I’m not sure how to do it.

The results of 12 days are 

1 1/2 quarts, 2 1/4 quarts, 2 quarts, 1 1/2 quarts, 1 3/4 quarts, 1 1/2 quarts, 1 1/4 quarts, 2 quarts, 2 1/4 quarts, 1 1/2 quarts, 2 quarts, and 1 1/2 quarts

This can also be written as 

3/2 quarts, 9/4 quarts, 2 quarts, 3/2 quarts, 7/4 quarts, 3/2 quarts, 5/4 quarts, 2 quarts, 9/4 quarts, 3/2 quarts, 2 quarts, 3/2 quarts 

Making denominator equal to 4 in all the results 

6/4 quarts, 9/4 quarts, 8/4 quarts, 6/4 quarts, 7/4 quarts, 6/4 quarts, 5/4 quarts, 8/4 quarts, 9/4 quarts, 6/4 quarts, 8/4 quarts, 6/4 quarts

Given that average = 1 3/4 quarts  = 7/4 quarts

On how many days did Keisha drink at least the average amount of water??

Now simply we can compare the results with the average value and count 

Number of days = 6 days ( all in bold) 

Now On day 13, Keisha drinks 1 quart of water.  means 4/4 quarts of water 

new average = (12  x 7/4 + 4/4)/13 = 22/13 = 1 9/13 

New average = 1 9/13  quarts

SI=(P*R*T)/100

P=2000

R=1.5

T=6

SI=(2000*1.5*6)/100

=(2000*9)/100

=180

Neil will earn interest of 180

The answer is in the image