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Let $S_{n}$ denote the sum of the first n terms of an arithmetic progression. If $S_{10} = 390$ and the ratio of the tenth and the fifth terms is $15 : 7$ , then $S_{15} - S_{5}$ is equal to:

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Important Questions on Sequences and Series

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Mathematics>Algebra>Sequences and Series>Arithmetic Progressions

x, y, z

are positive numbers in

A . P .

and

\tan^{- 1} x

\tan^{- 1} y

and

\tan^{- 1} z

are also in

A . P .

, then which of the following is correct.

MEDIUM

Mathematics>Algebra>Sequences and Series>Arithmetic Progressions

If the sum of the first

n

terms of the series

\sqrt{3} + \sqrt{75} + \sqrt{243} + \sqrt{507} + \dots

435 \sqrt{3},

then

n

equals:

HARD

Mathematics>Algebra>Sequences and Series>Arithmetic Progressions

The number of terms in an

A . P .

is even, the sum of the odd terms in it is

24

and that the even terms is

30 .

If the last term exceeds the first term by

10 \frac{1}{2},

then the number of terms in the

A . P .

MEDIUM

Mathematics>Algebra>Sequences and Series>Arithmetic Progressions

Let

a_{1}, a_{2}, a_{3}, \dots a_{n}, \dots

,be in A.P. If

a_{3} + a_{7} + a_{11} + a_{15} = 72

, then the sum of its first

17

terms is equal to :

HARD

Mathematics>Algebra>Sequences and Series>Arithmetic Progressions

For any three positive real numbers

a, b

and

c

. If

9 (25 a^{2} + b^{2}) + 25 (c^{2} - 3 a c) = 15 b (3 a + c) .

Then

MEDIUM

Mathematics>Algebra>Sequences and Series>Arithmetic Progressions

Let

a_{1}, a_{2}, a_{3}, \dots \dots, a_{49}

be in

A . P .

such that

Σ_{k = 0}^{12} a_{4 k + 1} = 416

and

a_{9} + a_{43} = 66 .

a_{1}^{2} + a_{2}^{2} + \dots + a_{17}^{2} = 140 m,

then

m

is equal to:

MEDIUM

Mathematics>Algebra>Sequences and Series>Arithmetic Progressions

a^{1 / x} = b^{1 / y} = c^{1 / z}

and

a, b, c

are in geometrical progression, then

x, y, z

are in

MEDIUM

Mathematics>Algebra>Sequences and Series>Arithmetic Progressions

Let

a_{1}, a_{2}, a_{3} . . .

be an

A . P .

with

a_{6} = 2 .

Then, the common difference of this

A . P .,

which maximise the product

a_{1} \cdot a_{4} \cdot a_{5},

is :

HARD

Mathematics>Algebra>Sequences and Series>Arithmetic Progressions

^{n} C_{4},^{n} C_{5}

and

^{n} C_{6}

are in A.P., then

n

can be

HARD

Mathematics>Algebra>Sequences and Series>Arithmetic Progressions

The houses on one side of a road are numbered using consecutive even numbers. The sum of the numbers of all the houses in that row is

170

. If there are at least

6

houses in that row and

a

is the number of the sixth house, then

MEDIUM

Mathematics>Algebra>Sequences and Series>Arithmetic Progressions

Let the sum of the first

n

terms of a non-constant

A . P ., a_{1}, a_{2}, a_{3}, . . . ., a_{n}

50 n + \frac{n (n - 7)}{2} A,

where

A

is a constant. If

d

is the common difference of this

A . P .

, then the ordered pair

(d, a_{50})

is equal to

HARD

Mathematics>Algebra>Sequences and Series>Arithmetic Progressions

Let the sum of the first three terms of an A.P. be

39

and the sum of its last four terms be

178

. If the first term of this A.P. is

10,

then the median of the A.P. is :

MEDIUM

Mathematics>Algebra>Sequences and Series>Arithmetic Progressions

If the sum and product of the first three terms in an

A . P .

are

33

and

1155

, respectively, then a value of its

11^{t h}

term is:

HARD

Mathematics>Algebra>Sequences and Series>Arithmetic Progressions

Given an A.P. whose terms are all positive integers. The sum of its first nine terms is greater than

200

and less than

220 .

If the second term in it is

12

, then its

4^{th}

term is :

HARD

Mathematics>Algebra>Sequences and Series>Arithmetic Progressions

The sum of all natural numbers

n

such that

100 < n < 200

and

H . C . F .

(91, n) > 1

MEDIUM

Mathematics>Algebra>Sequences and Series>Arithmetic Progressions

a_{1}, a_{2}, a_{3}, . . . .

are in A.P. such that

a_{1} + a_{7} + a_{16} = 40,

then the sum of the first

15

terms of this A.P is

EASY

Mathematics>Algebra>Sequences and Series>Arithmetic Progressions

Let

S_{n}

denote the sum of the first

n

terms of an

A . P .

. If

S_{4} = 16

and

S_{6} = - 48

, then

S_{10}

is equal to:

HARD

Mathematics>Algebra>Sequences and Series>Arithmetic Progressions

Let

a, b, c, d, e

be natural numbers in an arithmetic progression such that

a + b + c + d + e

is the cube of an integer and

b + c + d

is a square of an integer. The least possible value of the number of digits of

c

MEDIUM

Mathematics>Algebra>Sequences and Series>Arithmetic Progressions

Three positive numbers form an increasing

G . P .

If the middle term in this

G . P .

is doubled, the new numbers are in

A . P .

Then the common ratio of the

G . P .

is :

MEDIUM

Mathematics>Algebra>Sequences and Series>Arithmetic Progressions

The sum of all two digit positive numbers which when divided by

7

yield

2

5

as remainder is

Let Sn denote the sum of the first n terms of an arithmetic progression. If S10=390 and the ratio of the tenth and the fifth terms is 15 : 7, then S15−S5 is equal to:

Important Questions on Sequences and Series

Learn and Prepare for any exam you want !

Let $S_{n}$ denote the sum of the first n terms of an arithmetic progression. If $S_{10} = 390$ and the ratio of the tenth and the fifth terms is $15 : 7$ , then $S_{15} - S_{5}$ is equal to: