Quiz Discussion

If the average of x and 1/x(X\( \ne \)0) is M, then the average of x2 and 1/x² is :

• 1] 1 - M2
• 2] 1 - 2M2
• 3] 2M2 - 1
• 4] 2M2 + 1

The average score of a class of boys and girls in an examination is A. The ratio of boys and girls in the class is 3 : 1. If the average score of the boys is A + 1, the average score of the girls is-

• 1] A - 1
• 2] A - 3
• 3] A + 1
• 4] A + 3

The average price of 10 books is Rs.12 while the average price of 8 of these books is Rs.11.75. Of the remaining two books, if the price of one book is 60% more than the price of the other, what is the price of each of these two books?

• 1] Rs. 5, Rs.7.50
• 2] Rs. 8, Rs. 12
• 3] Rs. 16, Rs. 10
• 4] Rs. 12, Rs. 14

Sachin Tendulkar has a certain average for 11 innings. In the 12th innings he scores 120 runs and thereby increases his average by 5 runs. His new average is :

• 1] 60
• 2] 62
• 3] 65
• 4] 66

If the mean of a,b,c is M and ab+bc+ca=0, then the mean of a²,b²,c² is:

• 1]

  M²

• 2]

  3M²

• 3]

  6M²

• 4]

  9M²

When the average age of a couple and their son was 42 years, the son married and got a child after one year. When the child was 5 years old, the average age of the family became 36 years. What was the age of daughter-in- law at the time of their marriage ?

• 1] 23 years
• 2] 24 years
• 3] 25 years
• 4] 26 years

The mean weight of 34 students of a school is 42 kg. If the weight of the teacher be included, the mean rises by 400 grams. Find the weight of the teacher (in kg.)

• 1] 55 kg
• 2] 57 kg
• 3] 66 kg
• 4] 56 kg

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

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

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