Which number checks this equationX over 6 = 1 over 2

Question

Which number checks this equation. X over 6 = 1 over 2 .

Is it 6,4,3 or 12

Answer 1

Since you are asking which numbers checks for the equation, rather than how to solve it, I will demonstrate how to check the equation.

I believe the equation that you are checking is: x/6 = 1/2

We just need to substitute each value for x and reduce the fraction if it is possible

6/6 =1/2

1 = 1/2  This statement is false, so 6 does not check

4/6 = 1/2

2/3 = 1/2  This statement is false, so 4 does not check

3/6 = 1/2

1/2 = 1/2 This statement is true, so 3 checks

12/6 = 1/2

2 = 1/2  This statement is false, so 12 does not check

The only number that checks for this problem is 3.

 

Answer 2

The equation is X/6 = 1/2. Typically the fastest way to solve these is to cross multiply; the numerator on the left hand side is mult by the denominator on the right hand side, and the numerator on the right is mult by the denom on the left. It makes no difference which way you start. So you would get:

2X = 1(6); now solve for x. Divide each side by 2 and you get that X is 6/2, or 3.

This is a proportion problem. Since the proportions are equal to each other the value of their ratio is also the same. For example, what if I wrote the following:

1/4 = 25/100. Here, 1/4 can be multiplied by 25/25 to give another proportion with the same ratio value, 25/100. Note that 25/25 is equal to 1, so it doesn't change the actual ratio. The value of the ratios is 0.25 for each one, so the proportions are the same even though they're represented in different ways. What if we erased the 25?  

1/4 = X/100

Remember, the numerator and denominator had to be mult by the same number to get an equivalent proportion. To find it, you might recognize that 100 is 25 times greater than 4 (or divide 100 by 4), then take that result and mult by the numerator on the LHS to give the value X, in this case is also 25.