tom took a 30 question multiple choice test. he got 5 pts for correct answers and lost 1 pt. for incorrect ones. he scored a total of 120 points. how many correct ones did he get?

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tom took a 30 question multiple choice test. he got 5 pts for correct answers and lost 1 pt. for incorrect ones. he scored a total of 120 points. how many correct ones did he get?

Solution:

Let x be the number of correct responses and y be the number of incorrect responses

x+y=30 ----------------- eq.1

Since he is given 5 points for each correct answer and he loss 1 point for each incorrect response then

5x-y=120--------- eq 2

Adding both equations 6x=150, and x= 150/6=25,

Substituting value for x in equation 1 then 25+y=30 and then y =5.

Tom got 25 correct responses.

THIS PROBLEM COULD BE SOLVE USING A RATIO TABLE

NUMBER CORRECT AND POINTS (A) NUMBER INCORRECT AND POINTS (B) POINTS (A-B)

30 --- (30X5) =150 0------- 0x1 150

29 (29 X 5)=145 1--------1X1 =1 144

28 (28 X5) =140 2-------- 2 X1=2 138

27 (27x5) = 135 3----------3x1=3 132

26 (26 x5) = 130 4--------- 4x1 =4 126

25 (25x5)=125 5----------5x1=5 120

Based on the table he scored 120 points which is the result of having 25 correct responses corect.

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