Problem of the Week - Middle School - Jan. 31, 2021 to Feb. 6, 2021

Middle School: 

Question: For the first six days of the week, Zelda posted three pictures per day on social media. How many does she need to post on the seventh day to have an average of four pictures posted per day for the whole week? 

Answer: 10 pictures

Solution:  Zelda posted one less than the desired average on each of the first six days. That means that to have an average of four per day, Zelda will have to post one picture for each day that was one short, and then four more for the last day: 6 + 4 = 10 pictures. Another way to solve this is find that Zelda will need a total of 28 pictures because 28 ÷ 7 = 4. So far, she has 3 × 6 = 18, so she needs 10 more.