NTPC Solved Placement Paper
1.Which one of the following numbers is completely divisible by 45?
E.None of these
Ex:45 = 5 x 9, where 5 and 9 are co-primes.
Unit digit must be 0 or 5 and sum of digits must be divisible by 9.
Among given numbers, such number is 202860.
2.A and B can together finish a work 30 days. They worked together for 20 days and then B left. After another 20 days, A finished the remaining work. In how many days A alone can finish the work?
Ex:(A + B)'s 20 day's work =(1/30)*20=2/3
Remaining work =1 -2/3= 1/3
Now,1/3 work is done by A in 20 days.
Therefore, the whole work will be done by A in (20 x 3) = 60 days.
3.Starting from my office, I react house 20 min late if I walk at 3 kmph. Instead, if I walk at 4 kmph, I reach the house 15 min early. How far is my house from my office?
Let the distance between office and house = 1 kmph.
Thus, time required at 3 kmph =1/3 hr = 20 min
And, time required at 4 kmph =1/4 hr = 15 min
difference = 20 - 15 = 5 min
actual difference = 20 + 15 = 35 min.
if difference is 5 min, distance = 1 km
if difference is 35 min, distance = 7 km.
4.A merchant marks his goods up by 75% above his cost price. What is the maximum % discount that he can offer so that he ends up selling at no profit or loss?
Ex:Let us assume that the cost price of the article = Rs.100
Therefore, the merchant would have marked it to Rs.100 + 75% of Rs.100 = 100 + 75 = 175.
Now, if he sells it at no profit or loss, he sells it at the cost price.i.e. he offers a discount of Rs.75 on his selling price of Rs.175
Therefore, his % discount =(75/175)x 100 = 42.85%
5.A boatman goes 2 km against the current of the stream in 1 hour and goes 1 km along the current in 10 minutes. How long will it take to go 5 km in stationary water?
C.1 hr 15 min
D.1 hr 30 min
Ex:Rate downstream =(1/10)x 60 km/hr = 6 km/hr
Rate upstream = 2 km/hr.
Speed in still water = 1/2(6 + 2) kmph = 4 kmph.
? Required time =5/4hrs =15/14hrs = 1 hr 15 min.
6.How many times are the hands of a clock at right angle in a day?
Ex:In 12 hours, they are at right angles 22 times.
? In 24 hours, they are at right angles 44 times.
7.A series dissipative regulator is an example of a:
A. linear regulator
B. switching regulator
C. shunt regulator
D. dc-to-dc converter
8.The output voltage of a typical thermocouple is
A. Less than 100 mV
B. Greater than 1 V
C. Thermocouples vary resistance, not voltage.
D. None of the above
9.Temperature sensing can be achieved by the use of
D. All of the above
10.The change in value of an analog signal during the conversion process produces what is
A. Quantization error
B. Resolution error
C. Nyquist error
D. Sampling error
11.Holding current for an SCR is best described as
A. The minimum current required for turn-off
B. The current required before an SCR will turn on
C. The amount of current required to maintain conduction
D. The gate current required maintaining conduction
12.What does a Hall Effect sensor sense?
C. Magnetic fields
13.What type of application would use a photovoltaic cell?
A. An automobile horn
B. A TI 92 calculator
C. A magnetic field detector
D. A remote power source
14.The difference between scientific and engineering notation is
A. powers of ten representation
B. single vs. multiple digits before decimal point
C. groupings of multiples of three digits
D. All of the above
15.Pico is what relation to micro?