Quiz Discussion

There are 30 students in a class. The average age of first 10 students is 12.5 years. The average age of the remaining 20 students is 13.1 years. The average age (in years) of the students of the whole class is :

• 1] 12.5 years
• 2] 12.7 years
• 3] 12.8 years
• 4] 12.9 years

In Arun's opinion, his weight is greater than 65 kg but less than 72 kg. His brother doest not agree with Arun and he thinks that Arun's weight is greater than 60 kg but less than 70 kg. His mother's view is that his weight cannot be greater than 68 kg. If all are them are correct in their estimation, what is the average of different probable weights of Arun?

• 1]

  67 Kg

• 2]

  68 Kg

• 3]

  69 Kg

• 4]

  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 reduction in the speed of an engine is directly proportional to the square of the number of bogies attached to it. The speed of the train is 100 km/hr when there are 4 bogies and 55 kmph when there are 5 bogies. What is the maximum number of bogies that can be attached to the train so that it can move?

• 1]

  4

• 2]

  5

• 3]

  6

• 4]

  7

David obtained 76, 65, 82, 67 and 85 marks (out of 100) in English, mathematics, physics, chemistry and biology. What are his average marks?

• 1] 65
• 2] 69
• 3] 75
• 4] None of these

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

There are two sections A and B of a class, consisting of 36 and 44 students' respectively. If the average weight of section A is 40kg and that of section B is 35kg, find the average weight of the whole class.

• 1] 30 kg
• 2] 35 kg
• 3] 42.5 kg
• 4] 37.25 kg

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

The average of 20 numbers is zero. Of them, at the most, how many may be greater than zero ?

• 1]

  0

• 2]

  -1

• 3]

  1

• 4]

  None Of These

The average age of P, Q and R is 15 years more than R's age. If the total age of P and Q together is 39 years, then R's age is ?

• 1] 12 years
• 2] 24 years
• 3] 16 years
• 4] 14 years