Average test 3-Solved questions with detailed explanations for SSC, IBPS, SBI PO, RRB, RBI, CSE, CGL, CHSL, CDA, CSE, UPSC

6)

The average height of 16 students is 142 cm. If the height of the teacher is included, the average height increases by 1 cm. The height of the teacher is

[Corporation Bank, 2009]

A)
156 cm
B)
159 cm
C)
158 cm
D)
157 cm
E)
159.5 cm

Answer: Option B

Explanation

Here we can use the formula

$Average (A)= \frac{Sum of observations (S)}{No . of observations (N)} ⇒ S=A×N$

According to the question,

Sum of height of 16 students (A=142, N=16)

⇒S=142 X 16 =2272

Later, the height of the teacher included, the average height increases by 1 cm. (so A=143, N=17)

So, sum of height of 16 students and a teacher

⇒S=143 X 17 =2431

Now,

Height of the teacher =(sum of height of 16 students)-(Sum of height of 16 students and a teacher)

=2431-2272

= 159 cm.

Hence, Option B is correct.

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Discussion

7)

In a cricket team, the average age of 11 players and the coach is 18 yr. If the age of the coach is not considered, then the average decreases by 1 year. Find out the age of the coach?

A)
29 yr
B)
30 yr
C)
20 yr
D)
25 yr
E)
None of these

Answer: Option A

Explanation

Here we can use the formula

$Average (A)= \frac{Sum of observations (S)}{No . of observations (N)} ⇒ S=A×N$

According to the question,

Sum of 12 players age (A=18, N=12)

⇒S=18 X 12 =216

Later, If the age of the coach is not consider, the average decrases by 1 yr. (so A=17, N=11)

So, sum of 11 players age

⇒S=17 X 11 =187

Now,

The age of the coach =(sum of 12 players age)-(Sum of 11 players age)

=216-187

=29 yr.

Hence, Option A is correct.

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Discussion

8)

The average run scored by a batsman in 20 innings is 32. After 21st innings, the run average becomes 34. How much runs does the batsman score in his 21st innings?

A)
16
B)
55
C)
74
D)
45
E)
None of these

Answer: Option C

Explanation

Here we can use the formula

$Average (A)= \frac{Sum of observations (S)}{No . of observations (N)} ⇒ S=A×N$

According to the question,

Sum of runs in 20 innings (A=32, N=20)

⇒S=32 X 20 =640

After, 21st innings, the runs become 34 (so A=34, N=21)

So, sum of runs in 21st innings

⇒S=34 X 21 =714

Now,

Score of 21st innings =(sum of runs in 20 innings)-(Sum of runs in 21st innings)

=714-640

=74.

Hence, Option C is correct.

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Discussion

9)

The average age of 3 friends is 32 yr. If the age of the fourth friend is added, their average age comes out to be 31 yr. what is the age of the fourth friend?

A)
32 yr
B)
28 yr
C)
24 yr
D)
26 yr
E)
None of these

Answer: Option B

Explanation

Here we can use the formula

$Average (A)= \frac{Sum of observations (S)}{No . of observations (N)} ⇒ S=A×N$

According to the question,

Sum of 3 friends age (A=32, N=3)

⇒S=32 X 3 =96

Later, the age of 4th friend added, the average come out to be 31 yr (so A=31, N=4)

So, sum of 4 friends age

⇒S=31 X 4 =124

Now,

Age of the 4th friend =(sum of 3 friends age)-(Sum of 4 friends age)

=124-96

=28 yr.

Hence, Option B is correct.

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Discussion

10)

The average age of 20 school cricketers is 12 yr. When the age of the coach is included the average becomes 15 yr. Find the age of the coach.

A)
84 yr
B)
74 yr
C)
68 yr
D)
75 yr
E)
None of these

Answer: Option D

Explanation

Here we can use the formula

$Average (A)= \frac{Sum of observations (S)}{No . of observations (N)} ⇒ S=A×N$

According to the question,

Sum of 20 school cricketers age (A=12, N=20)

⇒S=12 X 20 =240

Later, Age of the coach included, the average becomes 15 yr (so A=15, N=21)

So, sum of 20 cricketers and a coach age

⇒S=15 X 21 =315

Now,

The age of the coach =(sum of 20 school cricketers age)-(Sum of 20 cricketers and a coach age)

=315-240

=75

Hence, Option D is correct.

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Discussion

Average Test-3 (Addition or Elimination of Items)

Answer: Option B

Answer: Option A

Answer: Option C

Answer: Option B

Answer: Option D