Question

Alan solved the proportion StartFraction x over 200 EndFraction = StartFraction 8 over 25 EndFraction as shown. StartFraction x over 200 EndFraction = StartFraction 8 over 25 EndFraction. (8) (x) = (25) (200). 8 x = 5,000. StartFraction 8 x over 8 EndFraction = StartFraction 5,000 over 8 EndFraction. X = 625. What is Alan's error?

Answer 1

He should have cross-multiplied 8×200 to get 1600, then divide 1600÷25=64

Explanation:

Use logic. If the numerator of the given fraction is less than half of the denominator, the value of x will have to be less than half of 200.

It is also possible to see that the denominator 25 is a factor of 200. If you know that 25×8=200, you can multiply the numerator 8×8 to get 64.

Answer 2

C. He mixed up the positions of 8 and 25 in the equation (8) (x) = (25) (200).

Explanation:

So, he mixed up the positions of 8 and 25 in that equation because he was trying to use cross products. He didn't cross-product them correctly, it was supposed to be 25x = 8 (200), but instead he just multiplied the numbers beside the other. I don't know if this makes sense and I'm sorry if it doesn't, but hope it does! ^^