General Mathematics

Question: The average of ten numbers is `7`.If each number is multiplied by `12`,then the average of new set of numbers is :
A
`7`

B
`19`

C
`82`

D
`84`

Note: Average of new set `= (12 xx 7)` `= 84`.
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Question: A man spends Rs `1800` monthly on an average for the first four months and Rs `2000`monthly for the next eight months and saves Rs `5600` a year .His average monthly income is:
A
`Rs 2000`

B
`Rs 2200`

C
`Rs 2400`

D
`Rs 2600`

Note: Total annual income `= Rs (1800 xx 4 + 2000 xx 8 + 5600)` `= Rs 28800`. :. Average monthly income `Rs ((28800)/12)` `= Rs 2400`.
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Question: The average age of `30`students of a class is `12` years .The average age of a group of `5`of the students is `10`years and that of another group of `5`of them is `14` years . What is the average age of the remaining students ?
A
`8 years`

B
`10 years`

C
`12 years`

D
`14 years`

Note: Total age of `20`students `= (30 xx 12) - (5 xx 10 + 5 xx 14)` `= 240 years` :. Required average `= (240/20)` `= 12 years`
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Question: A class has two section, in one of which there are `40`students with an average of `14.5` years .The average of the class is `14.2`years .If there be `32`students in the other section ,its average age is :
A
`13.5 years`

B
`13.6 years`

C
`13.7 years`

D
None

Note: Total age of `32`students `= (72 xx 14.2 - 40 xx 14.5) years` `= (1022.4 - 580) years` `= 442.4 years` :. Required average `= 442.4/32` `= 13.825 years`
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Question: The average of `50`numbers is `38`.If two numbers, namely `45`and `55` are discarded,the average of the remaining numbers is :
A
`36.5`

B
`37`

C
`37.5`

D
`37.52`

Note: Total sum of `48` numbers `= [50 xx 38 - (45 + 55)]` `= 1800` :. Required average `= 1800/48` `= 37.5`.
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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 :
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`
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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`
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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`
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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

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Question: The average of ten numbers is `7`.If each number is multiplied by `12`,then the average of new set of numbers is :

Question: A man spends Rs `1800` monthly on an average for the first four months and Rs `2000`monthly for the next eight months and saves Rs `5600` a year .His average monthly income is:

Question: The average age of `30`students of a class is `12` years .The average age of a group of `5`of the students is `10`years and that of another group of `5`of them is `14` years . What is the average age of the remaining students ?

Question: A class has two section, in one of which there are `40`students with an average of `14.5` years .The average of the class is `14.2`years .If there be `32`students in the other section ,its average age is :

Question: The average of `50`numbers is `38`.If two numbers, namely `45`and `55` are discarded,the average of the remaining numbers is :

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 :