SAT Ratios

Correct Answer: C

Solution:

Since none of the answers contains decimals, let's manipulate the ratio $1.25:1.5$ so that it also contains no decimals.

$1.25:1.5=\frac{1.25}{1.5} = \frac{125}{150} = \frac{5}{6}=5:6.$

We could obtain the same result if we multiply the ratio by $4,$ like this:

$4\cdot(1.25:1.5)=5:6.$

Of the choices, (A) and (B) are in simplified form and they don't equal $5:6$ . We eliminate them. Simplifying (C), we obtain $5:6$ , which matches our result and is the correct answer. Note that simplifying (D) yields $5:1 \neq 5:6,$ and simplifying (E) yields $25:3 \neq 5:6.$

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Incorrect Choices:

(A)
If you multiply the ratio by $2,$ you will obtain $2.5:3.$ If you then ignore the decimal, you will get this wrong answer.

(B)
If $a\neq b$ then $a:b\neq b:a,$ so $5:6 \neq 6:5.$

(D)
Tip: Just because a number appears in the question doesn’t mean it is the answer.
This wrong choice is derived from the decimal parts of the two numbers $1.25$ and $2.5.$

(E)
Tip: Just because a number appears in the question doesn’t mean it is the answer.
This wrong choice ignores the decimal points in the given numbers.