1.
The average age of class of 24 students is 24 years. The average increased by 1 when the teacher's age is also included. What is the teacher's age?
• A.
45
• C.
49
• B.
47
• D.
48
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Explanation :

 Avg x Number = Total

 24 years x 24 nos = 576 years ...(1)

 25 years x 25 nos = 625 years ...(2)

 Teachers age = (2) - (1)

 = 625 - 576 = 49 years.

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2.
When the present age of the mother is added to the present age of the daughter, the sum is 40 years. What will be their total ages after 5 years?
• A.
40 years
• C.
35 years
• B.
45 years
• D.
50 years
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Explanation :
 Let the present age of mother be x Daughter's age = 40 - x After 5 years, mother's age = x + 5 Daughter's age = 40 - x + 5 Total age = x + 5 + 40 - x + 5 = 50 years
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3.
The average of class of 30 students is 21 years. When the teacher's age is included, the average increases by 1. What is teacher's age?
• A.
50
• C.
55
• B.
51
• D.
52
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Explanation :

 Avg x Number = Total

 30 nos x 21 years = 630 years ...(1)

 30 nos x 22 years = 682 years ...(2)

 Teacher's age = (2) - (1) = 682 - 630 = 52 years.

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4.
The average age of class of 20 students is 20 years. If the teacher's age is included the average increases by 1. What is the age of the teacher?
• A.
40
• C.
31
• B.
41
• D.
42
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Explanation :

 Avg x Number = Total

 20 nos x 20 years = 400 ...(1)

 21 nos x 21 years = 441 ...(2)

 Teacher's age = (2) - (1) = 441 - 400 = 41 years.

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5.
The sum of the ages of a father and his two sons who are twins is 48. Ten years hence, his age will be twice the sum of the son�s ages. Find the present age of one son.
• A.
13 years
• C.
8 years
• B.
9 years
• D.
3 years