Quiz Discussion

What is the sum of the first 9 terms of an arithmetic progression if the first term is 7 and last term is 55?

• 1] 219
• 2] 279
• 3] 231
• 4] 137

Consider an infinite G.P. with first term a and common ratio r, its sum is 4 and the second term is 3/4, then

• 1]

  a = 7/4, r = 3/7

• 2]

  a = 2, r = 3/8

• 3]

  a = 3, r = 1/4

• 4]

  a = 3/2, r = ½

If S1 is the sum of an arithmetic progression of ‘n’ odd number of terms and S2 is the sum of the terms of the series in odd places, then \(\frac{{{S_1}}}{{{S_2}}}\)

• 1]

  \(\frac{{2n}}{{n + 1}}\)

• 2]

  \(\frac{n}{{n + 1}}\)

• 3]

  \(\frac{{n + 1}}{{2n}}\)

• 4]

  \(\frac{{n - 1}}{n}\)

How many 2-digit positive integers are divisible by 4 or 9?

• 1]

  32

• 2]

  22

• 3]

  34

• 4]

  30

For A.P. T18 - T8 = ........ ?

• 1] d
• 2] 10d
• 3] 26d
• 4] 2d

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

(1) + (1 + 1) + (1 + 1 + 1) + ....... + (1 + 1 + 1 + ...... n - 1 times) = ......

• 1]

  \(\frac{{n\left( {n + 1} \right)}}{2}\)

• 2]

  \(\frac{{n\left( {n - 1} \right)}}{2}\)

• 3]

  \({n^2}\)

• 4]

  n

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

If sum of n terms of an A.P. is 3n² + 5n and T^m = 164 then m =

• 1]

  26

• 2]

  27

• 3]

  28

• 4]

  None Of This

How many terms are there in the GP 5, 20, 80, 320........... 20480?

• 1] 5
• 2] 6
• 3] 8
• 4] 9
• 5] 7