RRB NTPC - Simplifications

1.

If 13 + 23 + ..... + 93 = 1025 then the value of (0.07)3 + (0.14)3 + (0.21)3 + ..... +(0.63)3 Is close to

   A.) 0.351575
   B.) 0.251575
   C.) 2.515575
   D.) 3.51575

Answer: Option 'A'

0.351575

2.

If 13 + 23 + 33 +......+ 103 = 516 then the value of 23 + 43 + 63 + ..... + 203 is

   A.) 1013
   B.) 1032
   C.) 516
   D.) 900

Answer: Option 'B'

2(13 + 23 + 33 + ---------- + 103)
2 × 516 = 1032

3.

√4225

   A.) 55
   B.) 95
   C.) 65
   D.) 45

Answer: Option 'C'

65

4.

√169/65 = 1/?

   A.) 3
   B.) 5
   C.) 7
   D.) 9

Answer: Option 'B'

5

5.

Find the value of
((0.1)3 + (0.6)3 + (0.7)3 − (0.3)(0.6)(0.7))/((0.1)2 + (0.6)2 + (0.7)2 − 0.006 − 0.42 − 0.07)

   A.) 14/10
   B.) 1.35
   C.) 13/10
   D.) 0

Answer: Option 'A'

((0.1)3 + (0.6)3 + (0.7)3 − (0.3)(0.6)(0.7))/((0.1)2 + (0.6)2 + (0.7)2 − 0.006 − 0.42 − 0.07)
=> (0.1 + 0.6 + 0.7)3/(0.1 + 0.6 + 0.7)2
=> 0.1 + 0.6 + 0.7 => 1.4 = 14/10

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