Average, General Mathematics

Question: The mean of `100`observations was calculated as `40`.It was found later on that one of the observations was misread as `83` instead of `53`.The correct mean is :
A
`39`

B
`39.7`

C
`40.3`

D
`42.7`

Note: Correct sum `= (40 xx 100 + 53 - 83)` `= 3970`. :. Correct mean `= 3970/100` `= 39.7`
1. Report
Question: The average of six numbers is `30`.If the average of first four is `25` and that of last three is `35`,the fourth number is :
A
`25`

B
`30`

C
`35`

D
`40`

Note: Fourth number `= (4 xx 25 + 3 xx 35 - 6 xx 60)` `= 25`
1. Report
Question: The average of `11` observation is `60`If the average of first five observations is `38`and that of the last five is `56`,then the sixth observation is :
A
`90`

B
`110`

C
`85`

D
`100`

Note: Sixth observation `= [60 xx 11 - (58 xx 5 + 56 xx 5)]` `= 90`
1. Report
Question: In seven given numbers ,the average of first four numbers is `4` and that of the last four numbers is also `4`.If the average of these seven numbers is `3`, the fourth number is :
A
`3`

B
`4`

C
`7`

D
`11`

Note: Fourth number `= (4 xx 4 + 4 xx 4 - 7 xx 3)` `= 11`
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Question: The average of `25` result is `18`.The average of first twelve of them is `14`and that of last twelve is `17`.The thirteenth result is :
A
`28`

B
`78`

C
`72`

D
`85`

Note: Thirteenth result `= [25 xx 18 - (12 xx 14 + 12 xx 17)]` `= 78`
1. Report
Question: Out of four numbers, the average of first three is `16` and that of the last three is `15`.If the last numbers is `18`the fisrt number is :
A
`20`

B
`21`

C
`23`

D
`25`

Note: Sum of 2nd & 3rd number `= (3 xx 15 -18)` `= 27` :. First number `= (3 xx 16 - 27)` `= 21`.
1. Report
Question: Mukesh has twiec as much money as Sohan and has `50‰`more money than what pankaj has. Ifthe average money with them is Rs `110`,then Mukes has :
A
`Rs 55`

B
`Rs 60`

C
`Rs 90`

D
`Rs 180`

Note: Not available
1. Report
Question: A motorist travels to a place `150`km away at an average speed of `50`km per hour and returns at `30`km per hour .His average speed for the whole journey in km per hour is :
A
`35`

B
`37`

C
`37.5`

D
`40`

Note: Average speed `= (2xy)/(x + y) km∕hr` `= ((2 xx 50 xx 30)/(50 + 30)) km∕hr` `= 37.5 km∕hr`
1. Report
Question: The total of the present ages of P Q R and S is `96` years. To find out Q,s present age,which of the following informations given in statements A and B is/are sufficient / A.The averagae age of P,Q,and S is `20` years B.The average age of R and S is `25` years
A
Both A and B are needed

B
Both A and B are not sufficient

C
Only B is sufficient

D
Only A is sufficient

Note: Clearly ,both A and B are not sufficient.
1. Report
Question: The average of `5`numbers is `7`.When `3` new numbers are added ,the average of the eight numbers is `8,.5`The average of the three new numbers is :
A
`11`

B
`7.75`

C
`8.5`

D
`7`

Note: Sum of three new numbers `= (8 xx 8.5 - 5 xx7)` `= 33` :. Thier average `= 33/3` `= 11`
1. Report

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

Question: The average of six numbers is `30`.If the average of first four is `25` and that of last three is `35`,the fourth number is :

Question: The average of `11` observation is `60`If the average of first five observations is `38`and that of the last five is `56`,then the sixth observation is :

Question: In seven given numbers ,the average of first four numbers is `4` and that of the last four numbers is also `4`.If the average of these seven numbers is `3`, the fourth number is :

Question: The average of `25` result is `18`.The average of first twelve of them is `14`and that of last twelve is `17`.The thirteenth result is :

Question: Out of four numbers, the average of first three is `16` and that of the last three is `15`.If the last numbers is `18`the fisrt number is :

Question: Mukesh has twiec as much money as Sohan and has `50‰`more money than what pankaj has. Ifthe average money with them is Rs `110`,then Mukes has :

Question: A motorist travels to a place `150`km away at an average speed of `50`km per hour and returns at `30`km per hour .His average speed for the whole journey in km per hour is :

Question: The total of the present ages of P Q R and S is `96` years. To find out Q,s present age,which of the following informations given in statements A and B is/are sufficient / A.The averagae age of P,Q,and S is `20` years B.The average age of R and S is `25` years

Question: The average of `5`numbers is `7`.When `3` new numbers are added ,the average of the eight numbers is `8,.5`The average of the three new numbers is :