BCA Family An online BCA community

### Surds and Indices

Given a sequence 1,4,16,20,36,49, find the odd one out [2013]

2

9

20

49

Look at this series 58,52,46,40,34,.... what number should come next[2013]

26

28

30

32

Look ar this series 7,10,8,11,9,12,.... what number should come next?[2013]

7

10

12

13

What is the nth of arthmetic series below? 3 + 7 + 11 + 15 + 19 [2013]

4n

34 + n

2n + 1

4n - 1

Let u represent the sum of the integer from 1 to 20, and v represent the sum of integers from 21 to 40. What is the value of v - u[2011]

39

200

320

400

Find the sum of the series 5 - 1+15 - ....[2009]

416

413

412

423

The Arithmetic mean of x and y is 10 and their geometric mean is 8. What is the value of x and y?[2007]

16.4

15.5

14.6

12.8

How many terms of the sequence 12, -9, -6, -3... must be taken to make sum 54?[2006]

13

12

14

11

If a sequence of 8 consecutive odd integer with increasing values has 9 as its seventh term, what is the sum of the terms of the sequence[2005]

22

32

36

40

### Other QUestions

What comes next in the sequence: 1, 2, 6, 22, ____ ?

82

84

86

88

what is the 11th term of the sequence: 1, 3, 9, 27, …. ?

28

210

38

310

Solutions

1,3,9 ,27, ... , a11 = ?
a1 = 1, r = 3, n = 11
an = a1rn-1
a11 = (1)(3)10
310

What is the sum of the first 100 natural numbers?

5,000

5,025

5,050

5,100

Solutions

${ n(n + 1)\over 2 }$ ${100 (100 + 1) } \over 2$
5050

What is the sum of the first 100 odd numbers?

9,000

10,000

11,000

12,000

Solutions

n2 = 1002

What is the 31st term of the sequence: 1, 4, 7, 10, …. ?

90

91

92

93

Solutions

1,4,7,10, ... , a31
an = a1 + (n - 1)d
a31 = 1 + (31 - 1)3
91

The fifth term of the sequence an = 2n + 3 is

I there is