﻿ Quantitative aptitude Question for all banking Bank PO,Clerk,IBPS PO,Railway,SSC,PSUs,IAS,OAS ,C-SAT Exams ﻿

### Mathmetics

ISBT Mathmetics for all banking PO,Clerk,IBPS PO,Railway,SSC,IAS,OAS Exams

##### What is value of the given sequence (53 + 63 + 73+…….. + 103) ?
 1) 2295 2) 2425 3) 2595 4) 2925 5) None of these
Explanation : We know that , the sum of the cube all natural number i.e. 1- n = [(n. n+1)/2]2

The sequence is  (13 + 23+ 33 + 43+  …….. + 103) -  (13 + 23+ 33 + 43)

So, [(10 x 11)/2]2 - [(4x5)/2]2 = 3025 -100 = 2925

##### The sum of the squares of two numbers is 68 and the square of their difference is 36. what is the product of the two numbers ?
 1) 16 2) 52 3) 58 4) 104 5) None of these
Explanation : Let, two  numbers are x and y respectively.
So, x2 + y2 = 68 and ( x - y )2 = 36.
We know that, ( x - y )2 = x2 + y2 - 2xy
or 68 - 2xy = 36
or 2xy = 68+36 = 104
or xy = 104/2=52

##### If doubling a number and adding 20 to the result gives the same answer as multiplying the number by 8 and taking away 4 from the product, then what is the number ?
 1) 2 2) 3 3) 4 4) 5 5) None of these
Explanation : Let, the number be x.
2x + 20 = 8x - 4
or 8x - 2x  = 20 + 4 = 24
or 6x =24
or x= 24/6= 4