Free Practice Question
PS · Problem Solving
705-805
Fractions/Ratios/Decimals
The ratio of a two digit number to a number formed by reversing its digits is 4:7. Which of the following is the sum of all the numbers of all such pairs?
Answer Choices
Correct answer marked belowA
110
B
200
330
Correct
D
88
E
770
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Explanation
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Official Explanation
Official
Let the two-digit number be and its reverse be .
Given:
So,
Expand:
Simplify:
Thus,
Since and are digits (1 through 9), possible pairs are:…
Given:
So,
Expand:
Simplify:
Thus,
Since and are digits (1 through 9), possible pairs are:…
Read the full explanation
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What it tests
Your ability to convert between fractions, ratios, and decimals and to reason proportionally.
Common trap
Cross-multiplying incorrectly or mixing up the ratio parts — a part:part ratio is not a fraction of the whole.
Details
Difficulty
705-805
Type
PS
Category