Question 1195418
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From 1958 to 1978, a span of 20 years, the percentage increased by 14.8%, from 83.2% to 98.0%.<br>
From 1958 to 1962 is a span of 4 years, so 1962 was 4/20 = 1/5 of the way from 1958 to 1978.  Since the rate of increase was constant, the increase in percentage from 1958 to 1962 was 1/5 of 14.8%, or about 3%. So<br>
ANSWER: The percentage in 1962 was about 83.2% + 3.0% = 86.2%.  Answer D<br>
More formally....<br>
Slope (i.e., rate of change) from 1958 to 1978 = (change in %) divided by (change in years) = (98.0-83.2)/(1978-1958) = 14.8/20 or about 15/20 = 3/4. So the percentage increased by about 3% every 4 years.<br>
1962 was 4 years after 1958, so the percentage in 1962 was about 3% greater than in 1958: 83.2% + 3% = 86.2%.<br>