Quiz Discussion

The nth term of an A.P., the sum of whose n terms is Sn, is

• 1] Sn + Sn - 1
• 2] Sn - Sn - 1
• 3] Sn + Sn + 1
• 4] Sn - Sn + 1

The sum of first n odd natural numbers in

• 1] 2n - 1
• 2] 2n + 1
• 3] n2
• 4] n2 - 1

The first term of an Arithmetic Progression is 22 and the last term is -11. If the sum is 66, the number of terms in the sequence are:

• 1] 10
• 2] 12
• 3] 9
• 4] 8

If three numbers be in G.P., then their logarithms will be in

• 1]

  AP

• 2]

  GP

• 3]

  HP

• 4]

   None Of This

If the fifth term of a GP is 81 and first term is 16, what will be the 4th term of the GP?

• 1] 36
• 2] 18
• 3] 54
• 4] 24
• 5] 27

In an A.P., if d = -4, n = 7, a_n = 4, then a is

• 1]

  6

• 2]

  7

• 3]

  20

• 4]

  28

A bacteria gives birth to two new bacteria in each second and the life span of each bacteria is 5 seconds. The process of the reproduction is continuous until the death of the bacteria. initially there is one newly born bacteria at time t = 0, the find the total number of live bacteria just after 10 seconds :

• 1]

  \(\frac{{{3^{10}}}}{2}\)

• 2]

  310 - 210

• 3]

  243 × (35 -1)

• 4]

  310 - 25

• 5]

  None of these

Let S denotes the sum of n terms of an A.P. whose first term is a. If the common difference d is given by d = S_n – k S_n-1 + S_n-2 then k =

• 1]

  1

• 2]

  2

• 3]

  3

• 4]

  4

The sum of n terms of an A.P. is 3n2 + 5n, then 164 is its

• 1] 24th term
• 2] 27th term
• 3] 26th term
• 4] 25th term

The sum of the first four terms of an A.P. is 56. The sum of the last four terms is 112. If its first term is 11, the number of terms is

• 1]

  10

• 2]

  11

• 3]

  12

• 4]

  13