Quiz Discussion

The average of 10 items was found to be 80 but while calculating, one of the items was counted as 60 instead of 50. Then the correct average would have been :

• 1] 69
• 2] 79.25
• 3] 79
• 4] 79.5

The average age of students of a class is 15.8 years. The average age of boys in the class is 16.4 years and that of the girls is 15.4 years. The ratio of the number of boys to the number of girls in the class is-

• 1] 1 : 2
• 2] 2 : 3
• 3] 3 : 4
• 4] 3 : 5

In a set of three numbers, the average of first two numbers is 2, the average of the last two numbers is 3, and the average of the first and the last numbers is 4. What is the average of three numbers?

• 1] 2
• 2] 2.5
• 3] 3
• 4] 3.5

The average of 9 observations was found to be 35. Later on, it was detected that an observation 81 was misread as 18. The correct average of the observation is -

• 1] 28
• 2] 42
• 3] 32
• 4] 45

If the mean of 4 observations is 20, when a constant 'c' is added to each observation, the mean becomes 22. The value of c is :

• 1]

  6

• 2]

  -2

• 3]

  2

• 4]

  4

A cricketer scored some runs in his 21st innings, as a result, his average runs increased by 3. If the present average run is 40, how many runs he scored in the final innings?

• 1] 103
• 2] 100
• 3] 85
• 4] 82

There were 35 students in a hostel. Due to the admission of 7 new student, the expenses of the mess were increased by Rs. 42 per day, while the average expenditure per head diminished by Re 1. What was the original expenditure of the mess?

• 1]

  432

• 2]

  442

• 3]

  420

• 4]

  415

A student finds the average of 10 positive integers. Each integer contains two digits. By mistake, the boy interchanges the digits of one number say ba for ab. Due to this, the average becomes 1.8 less than the previous one. What was the difference of the two digits a and b?

• 1] 8
• 2] 6
• 3] 2
• 4] 4

In the first 10 overs of a cricket game, the run rate was only 3.2. The run rate in the remaining 40 overs to reach the target of 282 run is :

• 1] 6.4
• 2] 6.3
• 3] 6.25
• 4] 6.5

The average of five different positive numbers is 25. x is the decrease in the average when the smallest number among them is replaced by 0. What can be said about x?

• 1] x is less than 5
• 2] x is greater than 5
• 3] x is equal to 5
• 4] Cannot be determined