Averages Quiz Set 020

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Question 1

Each of the 8 girls of a class has a score 28 marks. If a new girl with a score 56 marks more than the average of all 9 girls is added, what is the sum total of the values of all 9 girls?

 A

315 marks.

 B

316 marks.

 C

314 marks.

 D

313 marks.

Soln.
Ans: a

Let the average of all 9 girls be x, then the required total is T = 9x. By averages, $x = {8 × 28 + (x + 56)}/9$ which is same as $x × 9 = {8 × 28 + (x + 56)}$, which is same as $T = {8 × 28 + (T/9 + 56)}$, solving for T we get 315 marks.


Question 2

Average weight of a group of 25 boys is 46 Kg. Later it was found that the weighing machine was showing 3 Kg more than the actual weight. What is the actual average weight?

 A

43.

 B

44.

 C

42.

 D

41.

Soln.
Ans: a

Let the total weight of the group as measured with the faulty machine be x. Then, by average formula $46 = x/25$, which gives x = $46 × 25 = 1150$. When weight of each of the 25 boys is reduced by 3 Kg, the new total becomes $1150 - 25 × 3 = 1075$, the new average becomes $1075/25 = 43$. TIP: As a shortcut, the new average = old average - error in weighing machine.


Question 3

The average number of visitors at a zoo on a Monday is 72, whereas it is 108 on other days of the week. What will be the average number of visitors in a 30-day month that begins on a Monday?

 A

102.

 B

103.

 C

101.

 D

100.

Soln.
Ans: a

The month begins on a Monday, so there will be 5 Mondays. The average = ${5 × 72 + 25 × 108}/30$, which equals ${360 + 2700}/30$ = 102.


Question 4

387 men and 258 women are employed in a farm. The average wage per person is Rs. 128. What is the wage of a man if women are paid Rs. 5 less?

 A

Rs. 130.

 B

Rs. 131.

 C

Rs. 129.

 D

Rs. 132.

Soln.
Ans: a

Let the wage of a man and a woman be x and x - 5. We are given the average ${x × 387 + (x - 5) × 258}/{387 + 258}$ = 128. This equation can be solved for x to get Rs. 130 as the answer.


Question 5

Average marks of class of 20 students is 85. What will be the average if each student is given 6 as grace marks?

 A

91.

 B

92.

 C

90.

 D

89.

Soln.
Ans: a

Let the total score of the class before grace marks be x. Then, by average formula $85 = x/20$, which gives x = $85 × 20 = 1700$. When grace marks = 6 are added for each of the 20 students, the new total becomes $1700 + 20 × 6 = 1820$, the new average becomes $1820/20 = 91$. TIP: As a shortcut, the new average = old average + grace marks.


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This Blog Post/Article "Averages Quiz Set 020" by Parveen (Hoven) is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Updated on 2017-04-07.

Posted by Parveen(Hoven),
Aptitude Trainer


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