Question

Joanie believes that you cannot use cross products to solve the proportion StartFraction 50 over 3 EndFraction = StartFraction 75 over x EndFraction for x. She says that if you multiply both sides of the equation by x, you get StartFraction 50 x over 3 EndFraction = 75. Then, if you multiply both sides of the equation by 3, you get 50 x = 75, which is a different equation than you would get if you cross multiplied. What mistake did Joanie make in her reasoning?

Answer 1

Answer:

it is C

Step-by-step explanation:

i took the test on Edgeinuity

Answer 2

Given: Joanie believes that you cannot use cross products to solve the proportion StartFraction 50 over 3 EndFraction = StartFraction 75 over x EndFraction for x. She says that if you multiply both sides of the equation by x, you get StartFraction 50 x over 3 EndFraction = 75. Then, if you multiply both sides of the equation by 3, you get 50 x = 75, which is a different equation than you would get if you cross multiplied.

To find: The mistake Joanie made in her reasoning.

Solution:

The proportion that was given initially is

$\frac{50}{3} =\frac{75}{x}$

Then, x is multiplied on both sides of the equation.

$\frac{50}{3} * x =\frac{75}{x} * x$

$\frac{50x}{3} =75$

Now, 3 is multiplied on both sides of the equation.

$\frac{50x}{3} * 3 =75*3$

$50x = 75 *3$

But Joanie got the following equation.

$50x = 75$

Hence, it is evident that she did not multiply 3 on both sides, she only multiplied 3 on one side of the equation.

Therefore, the mistake Joanie made in her reasoning was not multiplying 3 on both sides of the equation.