Grades 7-8 Video Solutions 2021-video 2021 7-8/11

Video Transcription

Question 11. A rectangular chocolate bar consists of a grid of congruent chocolate squares.  The bar can be broken into two pieces by snapping it along a grid line. Neil breaks off a strip  of chocolate that is 2 squares wide and eats the 12 squares he obtains. Later, from the same bar, Jack breaks off a strip of chocolate that is 1 square wide and eats the 9 squares  he obtains. How many squares of chocolate are left in the bar? Since we know that Neil broke off a strip of chocolate that is 2 squares wide and there were 12 squares, we  know it was 6 squares long, so we can draw this, a 2 by 6 square. Next, we know that Jack broke off a strip of chocolate that was 1 square wide and 9 squares long, so we draw  this next to this square, since it has to be one solid piece of chocolate. Now we can fill in the gaps of what was missing from the chocolate bar. If we take away the chocolate  that was already eaten by Neil and Jack, then we are left with the remaining bar. If we count up all the squares that are left, we get 5 and 9. All we have to do now is multiply  these and get our solution, how many chocolate squares are left, and we get our answer, D, 45.

Video Summary

The chocolate bar initially has a grid of squares. Neil eats a 2-square-wide strip consisting of 12 squares, making it 6 squares long. Jack then eats a 1-square-wide strip consisting of 9 squares. After these portions are removed, the task is to determine the remaining number of squares. By visually piecing the bar back together and accounting for the removed portions, the remaining chocolate squares are found. The dimensions of the remaining bar are calculated as 5 by 9. Multiplying these gives the answer of 45 squares left in the chocolate bar.

Keywords

chocolate bar

squares

Neil

Jack

remaining