Quiz Discussion

What is the sum of the first 13 terms of an arithmetic progression if the first term is -10 and last term is 26?

• 1] 104
• 2] 140
• 3] 84
• 4] 98

Sum of n terms of the series \(\sqrt 2   +   \sqrt 8   +   \sqrt {18}   +   \sqrt {32}   +  \) ....... is

• 1]

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

• 2]

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

• 3]

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

• 4]

  1

The sum of first n odd natural numbers in

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

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

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

• 1] d
• 2] 10d
• 3] 26d
• 4] 2d

The first and last term of an A.P. is a and l respectively. If S is the sum of all the terms of the A.P. and the common difference is given by \(\frac{{{l^2} - {a^2}}}{{k - \left( {l + a} \right)}}\)   then k = ?

• 1] S
• 2] 2S
• 3] 3S
• 4] None of these

The 2nd and 6th term of an arithmetic progression are 8 and 20 respectively. What is the 20th term?

• 1] 56
• 2] 65
• 3] 59
• 4] 62

(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

The sum of the first 16 terms of an AP whose first term and third term are 5 and 15 respectively is

• 1] 600
• 2] 765
• 3] 640
• 4] 680
• 5] 690

How many terms are there in 20, 25, 30 . . . . . . 140?

• 1] 22
• 2] 25
• 3] 23
• 4] 24