Algebra 1b unit 4

Question

From a jar of pennies, 100 are drawn, marked, and returned to the jar. After mixing, a sample of 175 pennies is drawn. Of these, 11 are marked. Estimate the number of pennies in the jar, assuming that the ratio of marked pennies in the sample to total pennies in the sample equals the ratio of the total marked pennies to the total number of pennies in the jar. Round your answer to the nearest penny.

Answer 1

this seems to be a proportion problem. since a sample of 175 with 11 marked pennies have been established and with 100 pennies initially marked this proportion can be set up 11/175=100/x and when cross multiplied you get 11x=175 times 100 then divided by 11 into both sides to isolate x to get (100 times 175)/11 which is 1590.9090 and rounded to the nearest whole number the total number of pennies in the jar is 1591

Answer 2

11/175 = 100/?

11*? = 100*175

? = 100*175/11

?=1590

That is, 11/175 = 6 +2/7 % of the coins are marked