SOLUTION: In a test, Dora has answered only 4/5 of the questions and 3 of them are wrong. It is known that 4 marks are given for each correct answer, no marks for each wrong answer or any qu

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Question 1053870: In a test, Dora has answered only 4/5 of the questions and 3 of them are wrong. It is known that 4 marks are given for each correct answer, no marks for each wrong answer or any question not answered. If Dora gets 68 marks in the test, how many questions are there in the test?
Answer by Theo(13342) About Me  (Show Source):
You can put this solution on YOUR website!
let x equal the number of questions in the test.

she answered 4/5 * x.

she got all of them right except for 3.

this means she answered 4/5 * x - 3 correctly.

she got 4 marks for each correct answer and her total score was 68.

this means that (4/5 * x - 3) * 4 = 68

simplify to get 16/5 * x - 12 = 68.

add 12 go both sides of the equation to get 16/5 * x = 80

multiply both sides of the equation by 5/16 to get x = 80 * 5 / 16.

solve for x to get x = 25.

there were 25 questions on the test.

she answer 4/5 of them for a total of 20.

she got 3 wrong which means she got 17 right.

she gets 4 marks for every correct answer which means she got 4 * 17 = 68 total marks.

looks good to me.

solution is 25.