M1 Week 2 Challenge Q20
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Near a lake, 17% of the pollywogs eat 75% of the flies. If they had each eaten 7% more, what percent less do the rest of the pollywogs eat?
Your Answer
11.9
Correct Answer
21
Solution 1. Calculate consumption as flies per pollywog. For the 17% of pollywogs, they eat 75% x 1.07 percent of the flies, or 80.25% of the flies. This leaves 19.75% of the flies left for the remaining pollywogs, who before enjoyed 25% of the flies, so this is a reduction of 25%-19.25%=5.25% in their fly consumption. To get the percent less that the other pollywogs eat, we want the decrease divided by their previous consumption, or 5.25%/25% so the answer is 21%Hey, here's the question and what I'm confused of is why the 7% part is of 75% and not 100%. I mean, shouldn't the pollywogs have eaten 7% more of the total amount of flies?
And also, why do we need to divide the decrease by the previous consumption? For me, the percentage of the previous minus the percentage of the current looks good enough to be the answer.
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@fantasticcrow Okay so I think that the reason why it's 75 * 1.07 is because that's the new number of flies that have been consumed by the 17% of the pollywogs. Now as the number of flies remains constant, this means that there are 19.75% of flies remain to be eaten by the other 83% of the pollywogs. I hope that makes sense. My hint for you is to draw a table and/or maybe assume there are 100 pollywogs and 100 flies and go from there.
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Thanks! i think i kinda got it. Using your way of assuming there are 100 pollywogs and 100 flies, i figured that 17x7=119 which is bigger than 100, so each consuming 7% of the total amount would be impossible.
and that 7%was probably compared to their previous consumption. 
