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.

- a)450
- b)480
- c)510
- d)420

Correct answer is option 'B'. Can you explain this answer?

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."