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## Arithmetic

### Course: Arithmetic > Unit 2

Lesson 9: Comparing with multiplication# Comparing with multiplication and addition: giraffe

Sal solves 2 multiplication comparison word problems. Created by Sal Khan.

## Want to join the conversation?

- SO, according to the video the giraffe is just 2 times taller than shanntanu!

Look: G = 3xS = 18ft tall

G= 18ft tall; S = 6ft tall => G = 2xS taller than S

If the G = 3xS taller than S, the answer would be = 24ft tall!

I think the wording of the question should be like :" The giraffe has 3 times the height..."(36 votes)- what the heck does that mean(3 votes)

- and what is the point of this agian?(9 votes)
- the point is to use times? I think(9 votes)

- why are the equations so hard?(6 votes)
- They are not hard, you just dont understand them so you need to get more practice on this.(11 votes)

- but how do i do it?(8 votes)
- so if your multiplying like 1x1=1 because there is only one of it and if its like 2x0=0 because there is none of it(7 votes)

- its so ezz its 18 hight(8 votes)
- what in the world(10 votes)
- why is math important(9 votes)
- I think of math as a language that can describes certain concepts of the world in finite ways

Like for example if I wanted to figure out how much time will it take to fill up a tub of water at a rate of 5 ml/second then instead of literally timing myself adding 5 ml of water every second I use a form of math(in this case the problem I'm doing can be answer using volume and ratios)

Math can help people figure out the answer to a problem EXTREMELY fast and accurate without wasting time(the most important thing in life in my opinion)(2 votes)

- Dose E =mc square(7 votes)
- The examples you used are easy but in khan, it is hard. Can you use the question khan? please(6 votes)
- We're told that Imran is two years older than Diya. Diya is 2. How old is Imran? So I encourage you to pause this video and try to think about this yourself. How old is Imran given the information here? So let's use some letters to represent Imran and Diya's age. Let's say that I is equal to Imran's age. And let's say that D is equal to Diya's age. So given that, what does this first sentence tell us? It says that Imran's age, Imran is two years older than Diya. So Imran's age is going to be equal to Diya's age plus 2. That's what this first sentence tells us. Imran's age is Diya's age plus 2. Imran is two years older than Diya. Another way you could think about it, if we were to imagine their ages on a number line right over here, so if this is 0, and then this is Diya's age right over here-- let me do it in that same color. This is Diya's age right over here. If you were to add 2 to Diya's age, if you were to go to more, so plus 2, you would get to Imran's age. So that's what this first sentence tells us. Then they tell us that Diya is 2. So that's like saying that D, which we're using to represent Diya's age, that's going to be equal to 2. So this thing is equal to 2. So we can rewrite this as Imran's age is equal to Diya's age, which we know to be 2 plus 2. So what's 2 plus 2? Well, you know that. That's going to be 4. So Imran's age is going to be equal to 4. If this is 2 right over here, and then you were to go up 2 more, you're going to get to 4. Imran's age is 4. Let's try one more of these. So here we're told that the giraffe at the zoo is 3 times taller than Shantanu. Shantanu is 6 feet tall. How tall is the giraffe? So once again, I encourage you to pause this video and try to think about it on your own. Well, let's do the same idea. Let's use some letters to represent the different heights, so G for giraffe and S for Shantanu. I'll use G for the height of the giraffe. The height of the giraffe is 3 times taller-- not 3 more feet-- 3 times taller than Shantanu's height. So we could say that the giraffe's height is equal to 3 times Shantanu's height. So let's be clear. G represents the height of the giraffe, S represents the height of Shantanu. So another way of thinking about it-- let me see if I can draw a giraffe reasonably here. So if this is the giraffe-- actually, this isn't a bad job at drawing a giraffe. So this is the giraffe right over here. They're saying that if you take Shantanu's height times 3, you get to the giraffe's height. Actually, a giraffe might have longer legs than that. So this is G. The height of the giraffe is G. So let's say this is Shantanu's height. If I multiply that by 3, I get the giraffe's height. Let me see-- one, two. So Shantanu might look something like this. And if you took 3 times his height, so this is 1 time his height, 2 times his height, 3 times his height, you would get to the height of the giraffe. So that's what this first sentence tells us. Shantanu is 6 feet tall. So they tell us that this height right over here is 6 feet. Or another way of saying it is S is equal to 6 feet. How tall is the giraffe? Well, once again, S is equal to 6 feet. So the giraffe's height is equal to 3 times Shantanu's height, which we now know to be 6 feet, so 3 times 6 feet. So in feet, the giraffe's height is 3 times 6. Well, we know that 3 times 6 is 18. And we're dealing with feet. So the giraffe's height is 18 feet. And you see that right over here. 6 feet plus another 6 feet plus another 6 feet, or 6 feet times 3 is going to get you to 18 feet.(6 votes)

## Video transcript

We're told that Imran is
two years older than Diya. Diya is 2. How old is Imran? So I encourage you
to pause this video and try to think
about this yourself. How old is Imran given
the information here? So let's use some letters to
represent Imran and Diya's age. Let's say that I is
equal to Imran's age. And let's say that D
is equal to Diya's age. So given that, what does
this first sentence tell us? It says that Imran's age, Imran
is two years older than Diya. So Imran's age is going to be
equal to Diya's age plus 2. That's what this first
sentence tells us. Imran's age is
Diya's age plus 2. Imran is two years
older than Diya. Another way you
could think about it, if we were to imagine
their ages on a number line right over here,
so if this is 0, and then this is Diya's
age right over here-- let me do it in that same color. This is Diya's age
right over here. If you were to add
2 to Diya's age, if you were to go
to more, so plus 2, you would get to Imran's age. So that's what this
first sentence tells us. Then they tell us
that Diya is 2. So that's like
saying that D, which we're using to represent
Diya's age, that's going to be equal to 2. So this thing is equal to 2. So we can rewrite
this as Imran's age is equal to Diya's age,
which we know to be 2 plus 2. So what's 2 plus 2? Well, you know that. That's going to be 4. So Imran's age is
going to be equal to 4. If this is 2 right
over here, and then you were to go up 2 more,
you're going to get to 4. Imran's age is 4. Let's try one more of these. So here we're told that the
giraffe at the zoo is 3 times taller than Shantanu. Shantanu is 6 feet tall. How tall is the giraffe? So once again, I encourage
you to pause this video and try to think
about it on your own. Well, let's do the same idea. Let's use some
letters to represent the different heights, so G
for giraffe and S for Shantanu. I'll use G for the
height of the giraffe. The height of the
giraffe is 3 times taller-- not 3 more
feet-- 3 times taller than Shantanu's height. So we could say that
the giraffe's height is equal to 3 times
Shantanu's height. So let's be clear. G represents the
height of the giraffe, S represents the
height of Shantanu. So another way of
thinking about it-- let me see if I can draw
a giraffe reasonably here. So if this is the
giraffe-- actually, this isn't a bad job
at drawing a giraffe. So this is the giraffe
right over here. They're saying that if you
take Shantanu's height times 3, you get to the giraffe's height. Actually, a giraffe might
have longer legs than that. So this is G. The height
of the giraffe is G. So let's say this is
Shantanu's height. If I multiply that by 3, I
get the giraffe's height. Let me see-- one, two. So Shantanu might look
something like this. And if you took 3
times his height, so this is 1 time his height,
2 times his height, 3 times his height, you would get to
the height of the giraffe. So that's what this
first sentence tells us. Shantanu is 6 feet tall. So they tell us that this height
right over here is 6 feet. Or another way of saying
it is S is equal to 6 feet. How tall is the giraffe? Well, once again, S
is equal to 6 feet. So the giraffe's height is equal
to 3 times Shantanu's height, which we now know to be 6
feet, so 3 times 6 feet. So in feet, the giraffe's
height is 3 times 6. Well, we know that
3 times 6 is 18. And we're dealing with feet. So the giraffe's
height is 18 feet. And you see that
right over here. 6 feet plus another 6
feet plus another 6 feet, or 6 feet times 3 is going
to get you to 18 feet.