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Quiz: Average

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Number of Questions: 50

Question: 6 -

There were 35 students in a hostel. If the number of students increase by 7, the expenses of the mess increase by Rs 42 per day while the average expenditure per head diminishes by Rs 1. Find the original expenditure of the mess?

Options:

  1. 430

  2. 450

  3. 410

  4. 420

    5. Answer:

    420
    Solution:

    Suppose the average expenditure was Rs a.  Then total expenditure = 35a                                         When 7 more students join the mess, total expenditure = 35a + 42  Now, the average expenditure= (35a+42) / (35 + 7)                               Now, we have (35a + 42)/ 42 =(a – 1) or, 35a + 42 = 42a – 42 , 7a = 84 , a = 12

Question: 7 -

The difference between the average of first 52 even numbers and first 49 odd numbers is?

Options:

  1. -2

  2. 2

  3. 3

  4. 4

    5. Answer:

    4
    Solution:

    Average of first ‘n’ even no. = n+1, hence average of first 52 even no. = 52+1=53.                             Also, average of first ‘n’ odd no. = n, hence average of first 49 odd numbers = 49                                   Required difference = 53-49=4  

Question: 8 -

The average age of students of a class is 15.8 years. The average age of boys in the class is 16.4 years and that of the girls is 15.4 years. The ratio of the number of boys to the number of girls in the class is:

Options:

  1. 1:4

  2. 2:3

  3. 3:4

  4. 4:2

    5. Answer:

    2:3
    Solution:

    Let the ratio be k:1       Then, k x 16.4 + 1 x 15.4 = (k + 1) x 15.8                           (16.4 – 15.8) k = (15.8 – 15.4), k=2/3

Question: 9 -

The average age of a family of 6 members, 3 years ago was 28 years. Meanwhile a child was born in the family and the average age of the family members is 27 years today. What would be the age of the child so born, 2 years from now?

Options:

  1. 5 years

  2. 3 years

  3. 2 years

  4. 1 year

    5. Answer:

    5 years
    Solution:

    Average age of 6 members today is 28 + 3 = 31 years Let present age of the child be ‘x’ years.               So, (6×31+x)/7=27         186+x = 189,                   x=3years, 2 years from now, the age of the child would be 5 years.

Question: 10 -

The average of 11 numbers is 10.9. If the average of first six is 10.5 and that of the last six is 11.4 the sixth number is?

Options:

  1. 11.4

  2. 11

  3. 11.3

  4. 11.5

    5. Answer:

    11.5
    Solution:

    1 to 11 = 11 * 10.9 = 119.9    1 to 6 = 6 * 10.5 = 63               6 to 11 = 6 * 11.4 = 68.4       63 + 68.4 = 131.4 – 119.9 = 11.5                               6th number = 11.5