Solved Problems On Number And Tricks

Solved Problems 

1. How many digits will be there to the right of the decimal point in the product of 89.635 and .02218?

Answer: 7
Explanation:
Sum of decimal places = 3 + 5
= 8
The last digit to the extreme right is zero ( Since 5 * 8 = 40 )
Hence, there will be 7 significant digits to the right of the decimal point.
= 7


2. What least number should be added to 1056, so that the sum is completely divisible by 23?

Answer: 2
Explanation:
⇒ 1056 / 23
= 45
Remainder = 21
⇒ 21 + 2
= 23
Hence 2 should be added to 1056 so that the sum will be divisible by 23
= 2


3. If the average of five numbers is 10 and the sum of three numbers is 16, then what is the average of the other two numbers?

Answer: 17
Explanation:
Let the five numbers be a, b, c, d, e.
Average of (a + b + c + d + e ) / 5 = 10
Sum of three numbers = a + b + c
= 16
⇒ ( 16 + d + e ) / 5 = 10
16 + d + e = 50
d + e = 34
average of ( d + e ) = 34 / 2
= 17


4. In a group of ducks and buffaloes, the total number of legs are 24 more than twice the number of heads. Find the total number of buffaloes?

Answer: 12
Explanation:
Let the number of buffaloes be x.
Number of ducks be y.
⇒ 4x + 2y = [ 2 * ( x + y ) ] + 24
4x + 2y = ( 2x + 2y ) + 24
2x = 24
x = 24 / 2
x = 12


5. A number is divided by 406 leaves remainder 115, what will be the reminder when it will be divided by 29?

Answer: 28
Explanation:
Let the number be N.
So N = 406x + 115.
Now divide this number by 29.
As 406 is exactly divisible by 29, we have to divide 115 by 29 and find the remainder.
So remainder = 28


6. Price of 5 chairs and 2 tables is Rs. 1350. Two chairs cost as much as one table. What is the total price of one chair and one table?

Answer: Rs. 450
Explanation:
Let the cost of one table = Rs. x
Cost of 2 chairs = Rs. x
Cost of 1 chair = Rs. x / 2
Hence as per question,
5 ( x / 2 ) + 2x = 1350
5x + 4x = 2700
9x = 2700
x = 300
Total price of one chair and one table = Rs. [ ( x / 2 ) + x ]
= Rs. [ ( 300 / 2 ) + 300 ]
= Rs. 450


7. Find the median of 29, 23, 25, 29, 30, 25, 28

Answer: 28
Explanation:
Arranging the observations in the ascending order, we get
23, 25, 25, 28, 29, 29, 30.
N = Number of observations = 7, This is an odd integer.
∴ Median = [ ( N + 1 ) / 2 ]th term
= [ ( 7 + 1 ) / 2 ]th = 4th term in the ascending order data
= 28


8. Find the range of the data 27, 28, 34, 36, 39, 59. Also, find the coefficient of range?

Answer: Range = 32
Coefficient of range = 0.372
Explanation:
Here in the data, largest value L = 59
Smallest value S = 27
Range = L - S
= 59 - 27
= 32
Coefficient of range = ( L - S ) / ( L + S )
= ( 59 - 27 ) / ( 59 + 27 )
= 32 / 86
= 0.372


9. Find the value of 6 + [ 5 - { 4 + ( 3 - ( 2 + 1 ) } ]

Answer: Rs. 7
Explanation:
The rule to be followed for this type of problems is BODMAS and brackets in the order ( ), { }, [ ].
∴ 6 + [ 5 - { 4 + ( 3 - ( 2 + 1 ) } ]
= 6 + [ 5 - { 4 + ( 3 - 3 ) } ]
= 6 + [ 5 - { 4 + 0 } ]
= 6 + [ 5 - 4 ]
= Rs. 7


10. If an amount of Rs. 92070 is distributed amongst 135 persons. What is the amount that each person gets?

Answer: Rs. 682
Explanation:
Total amount = Rs. 92070
Amount distributed among 135 persons = 92070 / 135
= Rs. 682