Quiz Discussion

The average age of an adult class is 40 years. 12 new students with an average age of 32 years join the class, thereby decreasing the average by 4 years. The original strength of the class was-

• 1] 10
• 2] 11
• 3] 12
• 4] 15

A man travels equal distances of his journey at 40, 30 and 15 km/h. respectively. Find his average speed for whole journey.

• 1] 24
• 2] 25
• 3] 27
• 4] 28

The mean of 100 observations was calculated as 40. It was founder later on that one of the observation was misread as 83 instead of 53. The correct mean is :

• 1] 39
• 2] 39.7
• 3] 40.3
• 4] 42.7

There are five boxes in cargo hold. The weight of the first box is 200 kg and the weight of the second box is 20% higher than the weight of the third box, whose weight is 25% higher than the first box's weight. The fourth box at 350 kg is 30% lighter than the fifth box. Find the difference in the average weight of the four heaviest boxes and the four lightest boxes.

• 1] 51.5 kg
• 2] 75 kg
• 3] 37.5 kg
• 4] 112.5 kg
• 5] None of these

The average of 20 students is 12 years, if the teacher's age is included, average increases by one. The age of the teacher is:

• 1] 30 years
• 2] 33 years
• 3] 28 years
• 4] 35 years

The average age of three boys is 15 years. If their ages are in ratio 3 : 5 : 7, the age of the youngest boy is

• 1] 21 years
• 2] 18 years
• 3] 15 years
• 4] 9 years
• 5] 12 years

The average of 50 numbers is 30. If two numbers, 35 and 40 are discarded, then the average of the remaining numbers is nearly:

• 1] 28.32
• 2] 29.68
• 3] 28.78
• 4] 29.27

The average of six numbers is 3.95. The average of two of them is 3.4, while the average of the other two is 3.85. The average of the remaining two numbers is :

• 1] 4.6
• 2] 4.8
• 3] 4.5
• 4] 4.7

The average weight of 10 oarsmen in a boat is increased by 1.5kg when one of the crew who weighs 58kg is replaced by a new man.

• 1]

  73 Kg

• 2]

  64 Kg

• 3]

  12 Kg

• 4]

  34 Kg

In a school with 600 students, the average age of the boys is 12 years and that of the girls is 11 years. If the average of the school is 11 years 9 months, then the average the number of girls in the school is :

• 1] 150
• 2] 250
• 3] 350
• 4] 450