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If 75 percent of a class answered the first question on a certain test correctly, 55 percent answered the second question on the test correctly, and 20 percent answered neither of the questions correctly, what percent answered both correctly?

A. 10% B. 20% C. 30% D. 50% E. 65%

OA:E

I tried using the (group 1) + (group 2) - (neither) + (both) formula, but I seem that I cannot answer the question. What numbers do I need to plug in the above formula to receive E?

If 75 percent of a class answered the first question on a certain test correctly, 55 percent answered the second question on the test correctly, and 20 percent answered neither of the questions correctly, what percent answered both correctly?

A. 10% B. 20% C. 30% D. 50% E. 65%

OA:E

I tried using the (group 1) + (group 2) - (neither) + (both) formula, but I seem that I cannot answer the question. What numbers do I need to plug in the above formula to receive E?

Something doesn't seem right. If 65% answered both correctly, then how did only 55% answer the second question correctly.

Otherwise, it's D. 50% = both right, 25% = only A right, and 5% = only B right; finally 20% with none right.

why are you subtracting by 80, i know .20 did not get either question right but what logic did you use to say that you needed to subtract by 80? (besides 100-20 = 80)

I got this question in PowerPrep and the explanation had a graph... let me see if I can recall what it said.

...something like this.

How does C get calculated? I'm not understanding the Venn Diagram

C is what we're being asked to look for, the number of people that got both questions right.

75% 1st question right 55% 2nd question right

Remember that the people that got both questions right are contained within those two percentages.

As said before, 75+55 = 130-80= 50.

50% represents the number of people that got both questions correct, so in fact only 5% of the grand total got only the 2nd question right and 25% got only the 1st one right.