Quiz Discussion

The average of x number is y and average of y numbers is x. Then the average of all the numbers taken together is

• 1]

  (x+y)/2xy

• 2]

  2xy/(x+y)

• 3]

  (x²+y²)/(x+y)

• 4]

  xy/(x+y)

Distance between two stations A and B is 778km. A train covers the journey from A to B at 84 km per hour and returns back to A with a uniform speed of 56 km per hour. Find the average speed of train during the whole journey.

• 1]

  60 km/hr

• 2]

  30.5 km/hr

• 3]

  57 km/hr

• 4]

  67.2 km/hr

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

The average of five numbers is 306.4. The average of the first two numbers is 431 and the average of the last two numbers is 214.5. What is the third number?

• 1] 52
• 2] 108
• 3] 321
• 4] Cannot be determined
• 5] None of these

Find the average of the following sets of scores:385, 441, 876, 221, 536, 46, 291, 428

• 1] 221
• 2] 403
• 3] 428
• 4] 536
• 5] None of these

40% of the employees in a factory are workers. All the remaining employees are executives. The annual income of each worker is Rs. 390. The annual income of each executive is Rs. 420. What is the average annual income of all the employees in the factory together?

• 1] 390
• 2] 405
• 3] 408
• 4] 415

The average of nine number is 50. The average of first five numbers is 54 and that of the last three numbers is 52. Then the sixth number is :

• 1] 30
• 2] 34
• 3] 24
• 4] 44

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

The average age of 24 boys and their teacher is 15 years. When the teacher's age is excluded, the average age decreases by 1 year. The age of the teacher is :

• 1] 38 years
• 2] 39 years
• 3] 40 years
• 4] 41 years

The average age of the mother and her six children is 12 years which is reduced by 5 years if the age of the mother is excluded. How old is the mother ?

• 1] 40 years
• 2] 42 years
• 3] 48 years
• 4] 50 years