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Y is directly proportional to x, y=25 when x=5, what is x when y=60

User Jethro Cao
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1 Answer

3 votes

Answer:

x = 12

Explanation:

Directly proportional means that the factor remains constant. That factor is needed to go from one value to the next.

If y goes from 25 to 60. It means that the number 25 multiplied by a factor will result in the value of 60. To find the factor you simply have to divide the right numbers 60/25 ) = 2.4

Attention do not use 25/ 60 because that will reduce the number 25, rather then increase it. If that happens you know you have the numbers mixed up.

If y goes from 25 to 60 so understand and check that 25 * 2.4 = 60.

Now we need to apply the same factor with x.

So x goes from 5 to 5 * 2.4 = 12

So x = 12

OTHER METHOD

The ratio between x and y is important

5: 25 = x: 60

Write the ratios as if it were fractions.

5 / 25 = x / 60

Now solve for x (means, write in the form of x = ...)

x / 60 = 5 / 25

multiply left and right form the = sign by 60

x * 60 / 60 = 60 * 5 / 25

x * 1 = 300 / 25

x = 12

User DraganS
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