Current time:0:00Total duration:1:34

0 energy points

# Solving ratio problems with graph

In this example we'll plot points on the x and y axis to reflect the given ratios. Created by Sal Khan.

Video transcript

In a recent gum-chewing
contest, Violet tried to blow the biggest
blueberry-flavored bubble ever. Every 3 seconds, she
added 1 piece of gum to her huge bubble. On the graph below, the x-axis
represents time in seconds. So this right over
here is our x-axis. And the y-axis represents pieces
of gum in Violet's bubble. So this is the y-axis
right over here. Plot points to show
how many pieces of gum were in Violet's bubble
after 3, 6, and 9 seconds. So every 3 seconds, she
adds one piece of gum. So let me throw
all of my-- so what we care is about 3 seconds,
6 seconds, and 9 seconds. So every 3 seconds, we know
that she adds one piece of gum. This is 0 right over here. We're not going to worry
about negative time. So after 3 seconds, she would
have added one piece of gum to her bubble. Now, if 3 more seconds pass by,
she would have added 1 more, and now she would have 2
pieces of gum in her bubble. And then if 3 more seconds pass
by, now we're at 9 seconds, she would have added
1 more piece of gum, and now we're at 3
total pieces of gum. And notice, the ratio
between the pieces of gum and the time that has
passed has stayed constant, because she's doing
it at a constant rate. 1 to 3 is the same
ratio as 2 to 6, which is the same
ratio as 3 to 9. So, let's check our answer. Very good.