The information given below is regarding the number of students appeared in three different exams A, B and C in four different years 2015, 2016, 2017 and 2018.
In 2015:
Students appeared in exam A was twice the students appeared in exam B. Total students appeared in three exams together was 1640. Students appeared in exam B was 40 more than students appeared in exam C.
In 2016:
Students appeared in exam B was 40% more than students appeared in exam A while students appeared in exam C was 20% more than students appeared in exam B. Total students appeared in all three exams together was 2448.
In 2017:
Ratio of students appeared in exam A to exam B was 7:9. Students appeared in exam C was 25% more than students appeared in exam B. Total students appeared in all three exams together was 2180.
In 2018:
Average of students appeared in exams A and B was 560. Students appeared in exam C was 600. Ratio of students appeared in exam A to exam C was 4 : 5.
Q. What is the difference between number of students appeared in exams B and C together in 2015 and number of students appeared in exams A and B together in 2017?
  • a)
    450
  • b)
    480
  • c)
    510
  • d)
    420
Correct answer is option 'B'. Can you explain this answer?

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Answers

Aspire Academy
Jan 20, 2022
"In 2015
Let students appeared in exam B = a
Students appeared in exam A = 2a
Students appeared in exam C = a – 40
So a + 2a + a – 40 = 1640
4a = 1680
a = 420
Students appeared in exam B = 420
Students appeared in exam A = 840
Students appeared in exam C = 380
In 2017:
Let students appeared in exam A and exam B be 7c and 9c respectively.
Students appeared in exam C = 125% of 9c = 11.25c
So 7c + 9c + 11.25c = 2180
27.25c = 2180
c = 80
Students appeared in exam A = 560
Students appeared in exam B = 720
Students appeared in exam C = 900
Number of students appeared in exams B and C together in 2015 = 420 + 380 = 800
Number of students appeared in exams A and B together in 2017 = 560 + 720 = 1280
Difference = 1280 – 800 = 480
Hence, option B is correct."

"In 2015Let students appeared in exam B = aStudents appeared in exam A = 2aStudents appeared in exam C = a – 40So a + 2a + a – 40 = 16404a = 1680a = 420Students appeared in exam B = 420Students appeared in exam A = 840Students appeared in exam C = 380In 2017:Let students appeared in exam A and exam B be 7c and 9c respectively.Students appeared in exam C = 125% of 9c = 11.25cSo 7c + 9c + 11.25c = 218027.25c = 2180c = 80Students appeared in exam A = 560Students appeared in exam B = 720Students appeared in exam C = 900Number of students appeared in exams B and C together in 2015 = 420 + 380 = 800Number of students appeared in exams A and B together in 2017 = 560 + 720 = 1280Difference = 1280 – 800 = 480Hence, option B is correct."
"In 2015Let students appeared in exam B = aStudents appeared in exam A = 2aStudents appeared in exam C = a – 40So a + 2a + a – 40 = 16404a = 1680a = 420Students appeared in exam B = 420Students appeared in exam A = 840Students appeared in exam C = 380In 2017:Let students appeared in exam A and exam B be 7c and 9c respectively.Students appeared in exam C = 125% of 9c = 11.25cSo 7c + 9c + 11.25c = 218027.25c = 2180c = 80Students appeared in exam A = 560Students appeared in exam B = 720Students appeared in exam C = 900Number of students appeared in exams B and C together in 2015 = 420 + 380 = 800Number of students appeared in exams A and B together in 2017 = 560 + 720 = 1280Difference = 1280 – 800 = 480Hence, option B is correct."