RRB_exams > RRB > RRB_SE_Green_Answer_key_2014
PHYSICAL_SCIENCE > CHEMISTRY
1) Basalt is
A) a metamorphic rock and mostly contains felspar and pyroxeneB) a metamorphic rock and mostly contains quartz
C) an igneous rock and mostly contains felspar and pyroxeneD) an igneous rock and mostly contains quartz
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Answer : an igneous rock and mostly contains felspar and pyroxene


ENGINEERING > ELECTRICAL
2) Fire bricks are used to
A) reflect heatB) increase heat flow
C) decrease heat flowD) all of these
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Answer : decrease heat flow


PHYSICAL_SCIENCE > CHEMISTRY
3) In quick setting cement, the compound added is
A) aluminium sulphateB) aluminium silicate
C) calcium sulphateD) Gypsum
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Answer : aluminium sulphate


ENGINEERING > ELECTRICAL
4) If adhesion of reinforced concrete is not perfect
A) the concrete will be weak in compressionB) the concrete may break in tension
C) the steel be always overstressedD) none of these
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Answer : the steel be always overstressed


MATHEMATICS > Time_and_Distance
5) A train 110 metres long is running with a speed of 60 kmph. In what time will it pass the man who is running at 0 kmph in the direction opposite to that in which the train going
A) 5 secB) 6 sec
C) 7 secD) 10 sec
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Answer : 6 sec

\begin{aligned}\\ \text{Let Distance D = 110 m}\\ \text{Relative speed of train and man = 60 + 6}\\\text{ = 66 kmph (Since both are in moving in opposite direction)}\\ \text{= }\frac{66 * 10}{36}\text{ mps }\\ \text{= }\frac{110}{6}\text{ mps}\\ Time = \frac{distance}{speed}\\ = \frac{110}{\left(\frac{110}{6}\right)}\\ = 6 s \end{aligned}

MATHEMATICS > Time_and_Distance
6) A train 800 metres long is running at a speed of 78 km/hr. If it crosses a tunnel 1 minute, then the length of the tunnel (in meters) is
A) 130 mB) 360 m
C) 500 mD) 540 m
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Answer : 500 m

\begin{aligned} \text{S1 = 78 }\frac{km}{hr}\\ \text{L = 800 m}\\ \text{T = 1 min}\\ \text{Converting }\frac{km}{hr}\text{ to }\frac{m}{sec}\text{ using }\frac{5}{18}\\ \text{S1 = }\left(\frac{78 * 5 }{ 8}\right) \frac{m}{sec} = \left(\frac{65}{3}\right)\frac{m}{sec}\\ \text{Converting Time from min to sec}\\ \text{T = 1 min =60 sec}\\ \text{Let length of the tunnel beymetres}\\ \text{Therfore, }\left(\frac{800 + y}{60}\right)=\frac{65}{3}\\ \text{3 ( 800 + y ) = 3900}\\ \text{x = 500}\\ \end{aligned}

MATHEMATICS > ARITHMETIC
7) The square root of (7 + 3?5)(7 - 3?5) is
A) 5?5B) 2
C) 4D) 3?5
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Answer : 2


MATHEMATICS > GENERAL
8) A group of students decided to collect as many paise from each member of group as is the number of members. If the total collection amounts to Rs. 59.29, the number of the member is the group is
A) 51B) 61
C) 77D) 87
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Answer : 77


MATHEMATICS > GENERAL
9) If 3(x-y) = 27 and 3(x+y) = 243, then x is equal to
A) 0B) 2
C) 4D) 6
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Answer : 4


MATHEMATICS > GENERAL
10) What is the value of (256)0.16 iS x (256)0.09
A) 4B) 16
C) 64D) 256.25
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Answer : 4