Question Video: Using Proportions to Find Unknowns | Nagwa Question Video: Using Proportions to Find Unknowns | Nagwa

# Question Video: Using Proportions to Find Unknowns Mathematics • Third Year of Preparatory School

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Given that 21/π = 7/9 = π/36, find the values of π and π.

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### Video Transcript

Given that 21 over π is equal to seven over nine which is equal to π over 36, find the values of π and π.

First, we can just copy down the proportion. We notice that our only full fraction is the one in the middle β seven over nine. We can use this seven over nine to help us find π and π.

I know that to go from seven to 21, you multiply seven by three. I also know that when weβre working with fractions, if I multiply the numerator by a value, I must multiply the denominator by the same value. And that means that π must be equal to nine times three. Nine times three is 27. π is equal to 27.

We can use this same process to find π. I notice that nine times four equals 36. If I multiply the denominator by a value, I must multiply the numerator by the same value. Seven times four equals 28. π must be equal to 28.

The completed proportion looks like this: 21 over 27 is equal to seven over nine which is equal to 28 over 36.

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