# SOLUTION TO NTPC PLACEMENT PAPER

Jan 5 • General • 1513 Views • No Comments on SOLUTION TO NTPC PLACEMENT PAPER

.SOLUTION TO NTPC PLACEMENT PAPER.

GENERAL APTITUDE QUESTIONS:-

1 The expression (11.98 x 11.98 + 11.98 x x + 0.02 x 0.02) will be a perfect square for x equal to:

A.
 0.02
B.
 0.2
C.
 0.04
D.
 0.4

Explanation:

Given expression = (11.98)2 + (0.02)2 + 11.98 x x.

For the given expression to be a perfect square, we must have

11.98 x x = 2 x 11.98 x 0.02 or x   = 0.04

2.Simple interest on a certain sum of money for 3 years at 8% per annum is half the compound interest on Rs. 4000 for 2 years at 10% per annum. The sum placed on simple interest is:
A.
 Rs. 1550
B.
 Rs. 1650
C.
 Rs. 1750
D.
 Rs. 2000

Explanation:

C.I.
 = Rs. 4000 x 1 + 10 2 – 4000 100
 = Rs. 4000 x 11 x 11 – 4000 10 10
= Rs. 840.

 Sum = Rs. 420 x 100 = Rs. 1750. 3 x 8

3.A boat running downstream covers a distance of 16 km in 2 hours while for covering the same distance upstream, it takes 4 hours. What is the speed of the boat in still water?
A.
 4 km/hr
B.
 6 km/hr
C.
 8 km/hr
D.

Explanation:

 Rate downstream = 16 kmph = 8 kmph. 2

 Rate upstream = 16 kmph = 4 kmph. 4

 Speed in still water = 1 (8 + 4) kmph = 6 kmph. 2

4.A large tanker can be filled by two pipes A and B in 60 minutes and 40 minutes respectively. How many minutes will it take to fill the tanker from empty state if B is used for half the time and A and B fill it together for the other half?
A.
 15 min
B.
 20 min
C.
 27.5 min
D.
 30 min

Explanation:

 Part filled by (A + B) in 1 minute = 1 + 1 = 1 . 60 40 24

Suppose the tank is filled in x minutes.

 Then, x 1 + 1 = 1 2 24 40

 x x 1 = 1 2 15

x = 30 min.

5 .Out of 7 consonants and 4 vowels, how many words of 3 consonants and 2 vowels can be formed?
A.
 210
B.
 1050
C.
 25200
D.
 21400
E.
 None of these

Explanation:

Number of ways of selecting (3 consonants out of 7) and (2 vowels out of 4)

= (7C3 x 4C2)
 = 7 x 6 x 5 x 4 x 3 3 x 2 x 1 2 x 1
= 210.

Number of groups, each having 3 consonants and 2 vowels = 210.

Each group contains 5 letters.

 Number of ways of arranging 5 letters among themselves = 5! = 5 x 4 x 3 x 2 x 1 = 120.

Required number of ways = (210 x 120) = 25200

.

TECHNICAL QUESTIONS:-

2.If 750 µA is flowing through 11 k of resistance, what is the voltage drop across the resistor?
A.
 8.25 V
B.
 82.5 V
C.
 14.6 V
D.
 146 V

3.At the end of a 14 day period, your utility bill shows that you have used 18 kWh. What is your average daily power?
A.
 1.286 kWh
B.
 12.85 kWh
C.
 535 kWh
D.
 252 kWh

4.A half-watt is equal to how many milliwatts?
A.
 5,000 mW
B.
 5 mW
C.
 500 mW
D.
 50 mW

5.Series aiding is a term sometimes used to describe voltage sources of the same polarity in series.
A.
 True
B.
 False

6.If there are a total of 120 mA into a parallel circuit consisting of three branches, and two of the branch currents are 40 mA and 10 mA, the third branch current is
A.
 50 mA
B.
 70 mA
C.
 120 mA
D.
 40 mA

7.In a parallel circuit, the branch with the lowest resistance has the most current.
A.
 True
B.
 False

11.Third-order determinants are evaluated by the expansion method or by the cofactor method.
A.
 True
B.
 False

12.A 2 F, a 4 F, and a 10 F capacitor are connected in series. The total capacitance is less than
A.
 2 F
B.
 4 F
C.
 10 F
D.
 1.5 F

13.Five time constants are required for a capacitor to charge fully or discharge fully.
A.
 True
B.
 False

14.In an RL circuit, the impedance is determined by both the resistance and the inductive reactance combined.
A.
 True
B.
 False

15.A 10 resistor, a 90 mH coil, and a 0.015 F capacitor are in series across an ac source. The impedance magnitude at 1,200 Hz below fr is
A.
 1,616
B.
 161
C.
 3,387
D.
 1,771

16.A certain series RLC circuit with a 200 Hz, 15 V ac source has the following values: R = 12 , C = 80 F, and L = 10 mH. The total impedance, expressed in polar form, is
A.
 12.2812.34°
B.
 12.5712.34°
C.
 9.9512.34°
D.
 12.6212.34°

17.Referring to Problem 18, what is the bandwidth of the filter?
A.
 1 kHz
B.
 632 kHz
C.
 50.3 kHz
D.
 10.5 kHz

18.In an RC differentiator, the sum of the capacitor voltage and the resistor voltage at any instant
A.
 must be zero
B.
 must be equal to the applied voltage
C.
 is less than the applied voltage but greater than zero
D.
 cannot be determined

19.If the RC time constant of an integrator is increased, as the time constant is increased
A.
 the capacitor charges more during a pulse and discharges less between pulses
B.
 the capacitor charges less during a pulse and discharges more between pulses
C.
 the capacitor charges more during a pulse and discharges more between pulses
D.
 the capacitor charges less during a pulse and discharges less between pulses

20.In an RL integrating circuit, the output voltage is taken across the inductor.
A.
 True
B.
 False