Quiz Discussion

After striking the floor, a rubber ball rebounds to 4/5th of the height from which it has fallen. Find the total distance that it travels before coming to rest if it has been gently dropped from a height of 120 metres.

• 1] 540 m
• 2] 960 m
• 3] 1080 m
• 4] 1020 m
• 5] 1120 m

Find the nth term of the following sequence :

• 1]

  5(10n - 1)

• 2]

  5n(10n - 1)

• 3]

  \(\frac{5}{9} \times \left( {{{10}^n} - 1} \right)\)

• 4]

  \({\left( {\frac{5}{9}} \right)^n} \times \left( {{{10}^n} - 1} \right)\)

Which term of the A.P. 24, 21, 18, ............ is the first negative term?

• 1] 8th
• 2] 9th
• 3] 10th
• 4] 12th

If a, b, c are in A.P., then (a – c)²/ (b² – ac) =

• 1]

  3

• 2]

  4

• 3]

  1

• 4]

  2

What is the sum of all positive integers up to 1000, which are divisible by 5 and are not divisible by 2?

• 1] 10,050
• 2] 5050
• 3] 5000
• 4] 50,000

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

If an A.P. has a = 1, tn = 20 and sn = 399, then value of n is :

• 1] 20
• 2] 32
• 3] 38
• 4] 40

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

What is the sum of the following series? -64, -66, -68, ......, -100

• 1] -1458
• 2] -1558
• 3] -1568
• 4] -1664

If k, 2k – 1 and 2k + 1 are three consecutive terms of an AP, the value of k is

• 1] -2
• 2] 3
• 3] -3
• 4] 6