One roommate is saving to buy a house, so each month, he puts money aside in a special house savings account. The ratio of his monthly house savings to his rent is 1:3. If he pays $270 per month in rent, how much money does he put into his house savings account each month?
Correct Answer: A
Rationale: The ratio of his savings to his rent is 1:3, which means that for every $3 he pays in rent, he saves $1 for the purchase of a house. To calculate the amount saved, divide $270 by 3: $270 · 3 = $90. Therefore, he puts $90 into his house savings account each month. Choice B, $270, is incorrect because that is the amount he pays in rent, not the amount saved. Choices C and D, $730 and $810, are incorrect as they do not align with the 1:3 ratio described in the question.