Main content

## Topic A: Multiplicative comparison word problems

Current time:0:00Total duration:2:21

# Comparing areas word problem

CCSS Math: 4.MD.A.3

## Video transcript

Mary's rectangular poster
is 36 inches by 20 inches. Susan's rectangular poster
is 26 inches by 30 inches. Which poster has a larger area
and by how many square inches? So let's think about these. So this is Mary's poster. Mary's poster is 36
inches by 20 inches. So it's 36 inches by 20 inches. So it might look
something like that. So the area is going to be
36 times 20 square inches. 36 times 2 is 72. So 36 times 20 is going
to be 720 square inches. Now let's think about
Susan's situation. So let's draw Susan's poster. Susan's poster is 26
inches by 30 inches, so 26 inches by 30 inches. So Susan's poster might
look something like that. That's Susan's poster, my best
attempt to draw a rectangle. What's the area here? The area is 26 times
30 square inches, which is equal
to-- let's actually multiply this one
out-- 26 times 30. We could do 26 times 3 and
essentially add a 0 there. So 3 times 6 is 18. 3 times 2 is 6, plus 1 is 78. And actually, I could have
probably done that in my head. 3 times 20 is 60, plus 3
times 6 is 18, gets us 78. But this isn't 3 times 26. 3 times 26 would be 78. 30 times 26 is 780. So it's 780 square inches. So whose poster, which
poster has a larger area? Susan's. Susan's poster
has a larger area. And by how many square inches? Well, hers is 780 square
inches while Mary's is 720 square inches. So it's by 60 square inches. 780 minus 720 would be 60.