Average Marks and Weights Quiz

In a class of 50 students, the ratio of boys and girls is 2:3. The average marks of the boys is 60 and the average marks of the girls is 70. What is the average marks of the whole class?

• 65

• 66

• 67

• 64

Answer explanation

In a class of 50 students, there are 20 boys and 30 girls. Total marks of boys = 20*60 = 1200, and girls = 30*70 = 2100. Total marks = 1200 + 2100 = 3300. Average marks = 3300/50 = 66. Thus, the average marks of the whole class is 66.

A group of 19 students took an examination, another student joined the group after baking the examination. By including his marks, the average marks of the group increased by 1.5 marks. This student has scored ----- marks more than the average marks without including him.

• 25

• 30

• 24

• 28.5

Answer explanation

Let the average marks of 19 students be A. The total marks without the new student is 19A. After including the new student, the average becomes A + 1.5. Thus, the new total is 20(A + 1.5) = 20A + 30. The new student scored 30 marks more than A.

The average marks obtained by Suveer in 15 exams is 29. Ruchira has maintained the average of 27 but till now she has taken only 11 exams. What is the average score that Ruchira has to score in the remaining four exams to match Suveer's performance?

• 35

• 34.5

• 36

• 35.5

Answer explanation

Suveer has a total score of 15 * 29 = 435. Ruchira's current score is 11 * 27 = 297. To match Suveer, she needs 435 points. For 4 exams, she needs 435 - 297 = 138 points, averaging 138 / 4 = 34.5.

A group of seven students took an exam. After exam one more students joined the group. After including the new student the average marks is raised by 2. In comparison with the average marks of initial seven students, how much more marks did the new student obtain?

• 16

• 18

• 14

• 20

Answer explanation

Let the average of the first seven students be A. After adding the new student, the average becomes A + 2. The new student's marks must be 16 more than A to raise the average by 2, hence the correct answer is 16.

In a class the average marks obtained by 35 students is 63. If two more students whose average is 85.5 is add, to these then the new average of the class is?

• 64.20

• 67.90

• 63.62

• 65.35

Answer explanation

The total marks of 35 students = 35 * 63 = 2205. Adding 2 students with average 85.5 gives 2 * 85.5 = 171. New total = 2205 + 171 = 2376. New average = 2376 / 37 = 64.20. Thus, the correct answer is 64.20.

The average marks obtained by James in Maths, Science and History is 89. If the marks of Language is also added then the averages decreases to 88.25. Find out the marks obtained by him in the Language.

• 90

• 82

• 86

• 83

Answer explanation

James's average in three subjects is 89, so total marks = 3 * 89 = 267. Adding Language marks (L) gives an average of 88.25 for four subjects: (267 + L) / 4 = 88.25. Solving gives L = 86.

The average weight of 14 students of a class is 20 kg. If a student leaves the class the average weight of the class drops by 2 kg. Find the weight of the student (in kg) who left the class.

• 43

• 49

• 45

• 46

Answer explanation

The total weight of 14 students is 14 * 20 = 280 kg. After one student leaves, the average becomes 18 kg for 13 students, totaling 234 kg. The weight of the student who left is 280 - 234 = 46 kg.

The average age of 35 students of a class is 15 years, When the teacher's age is also included, then the average age increases by one year. Find the age of teacher.

• 45 years

• 51 years

• 41 years

• 35 years

Answer explanation

The total age of 35 students is 35 * 15 = 525 years. Including the teacher, the average becomes 16 years for 36 people, so total age is 36 * 16 = 576 years. Thus, the teacher's age is 576 - 525 = 51 years.

There are two sections, A and B of a class, consisting of 40 and 50 students, respectively. If the average weight of students in section A is 36 kg and that of those section B is 45 kg, then the average weight of the whole class is :

• 39 kg

• 43 kg

• 42 kg

• 41 kg

Answer explanation

To find the average weight of the whole class, calculate the total weight of both sections: (40 * 36) + (50 * 45) = 1440 + 2250 = 3690 kg. Then divide by the total number of students: 3690 / 90 = 41 kg.

Six years ago, the average age of L and M was 39 years and the average of the present ages of L, M and N is 54 years. What will be the age of N 5 years from now?

• 97 years

• 72 years

• 92 years

• 77 years

Answer explanation

Six years ago, L and M's average age was 39, so their total age was 78. Presently, L and M are 6 years older each, totaling 90. The average age of L, M, and N is 54, so N's age is 54*3 - 90 = 72. In 5 years, N will be 77.