TCS aptitude questions wid answer

1.In the class of 40 students, 30 speak Hindi and 20 speak
English. What
is the lowest possible number of students who speak both the
languages? ans:10
 (a) 5                       (b) 20            (c) 15      
          (d)
10                      (e) 30
Ans: formula: n(both)=n(English) + n(hindi) – n(total ppl)
   =20+30-40
   =10 ---- ans

2. A salesperson by mistake multiplied a number and got the
answer as 3,
instead of dividing the number by 3. What is the answer he
should have
actually got? ans:1/3
       (a) 0                   (b) 1/3                     
   (c) 1      
 (d) 2                   (e) 3

Assume 1
1*3=3
1*1/3=1/3
So he has got 1/3
This is answr

3. A tree grows only 3/5 as fast as the one beside it. In
four years the
combined growth of the two trees is eight feet. How much
does the shorter
tree grow in two years? ans: 1 ½ feet
 (a) Less than 2 feet  (b) 2 feet  (c) 1 1/2 feet (d) 3feet
              
    (e) more than 3 feet.

X=(3/5)y 
4(x+y)=8

Solvin these equation…u get answr…
Simple….


4. A family, planning a weekend trip, decides to spend not
more than a
total of 8 hours driving. By leaving early in the morning,
they can average
40 miles per hour on the way to their destination. Due to
the heavy Sunday
traffic, they can average only 30 miles per hour on the
return trip. What is the farthest distance from home they
can plan to go? ans: B
(a) 120 miles or less  (b) Between 120and 140 miles  (c) 140
miles (d)
Between 140 and 160 miles  (e) 160 miles or more
Avg speed= (x+y)/2xy=  (30+40)/2*30*40=avg speed..find
distance covrd in dis time by formula,, distance=speed*time
And continue wid thinkin
 (this prb cannot b solvd exclusively by formula...hav to
hav logical thinking) 




5. My flight takes of at 2am from a place at 18N 10E and
landed 10 Hrs
later at a place with coordinates 36N70W. What is the local
time when my
plane landed.
a) 6:00 am b) 6:40am c) 7:40 d) 7:00 e) 8:00 
ans: 4 hrs

here u hav to add the degrees…I mean 10+70=80 degrees..(10E
+ 70W)
I wil tel u the simpler way of solvin this ques…..
Nw 80*4=320 mins( multiplied by 4 bcoz 1degree=4 min)den
convert to hrs wch is 3hrs20min..
Nw the plane startd at 2 am n takes 10 hrs,,,so time dat it
shud reach is 12noon,,
the point to b noted here is dat wen plane is moving frm
EAST to WEST…u hav to subtract the time taken(320mins)frm
12noon…
wch becomes 12noon – 320 mins=6:40 am
gotit??

6. Given $ means Tripling and % means change of sign then
find the value
of $%$6-%$%6
ans: -72

(($%$6)-(%$%6))
here..tripling means multiplyin by 3 …
so 6 is multiplied by 3 two times in first pair of brackets
bcoz of 2 dollar signs..
in second part its multiplied by 3 once ..
in 1st part
ie…6*3=18
   18*3=54
   Nxt it bcomes -54 bcoz of % sign ….so first part is -54
In 2nd part   
   Its -18…(6*3)

So the eq bcomes -54-18=72/// ans  

7. B and C are 8 bit no's. They are as follows:
A 1 1 0 1 1 0 1 1
B 0 1 1 1 1 0 1 0
C 0 1 1 0 1 1 0 1
Find ( (A-B) u C )=? ans:109
first find (A-B)
so u hav to find 2’s complement of C and add wid A///
den find the union of both..ie OR gate..


8.If A, B and C are the mechanisms used separately to reduce
the wastage
of fuel by 30%, 20% and 10%. What will be the fuel economy
if they were
used combined. Ans:49.6%

simple…. (70/100)*(80/100)*(90/100)*100=50.4((( 70 comes frm
(100-30) and so on fr othrs…….)
         100-50.4=49.6  

9. The size of the bucket is N kb. The bucket fills at the
rate of 0.1 kb per millisecond. A programmer sends a program
to receiver. There it waits for 10 milliseconds. And
response will be back to programmer in 20 milliseconds. How
much time the program takes to get a response back to the
programmer, after it is sent? ans:30 ms
Dis does nt take to read ur prb in depth…
Jz luk fr the two time taken…… ie…10 milliseconds and 20
milliseconds…
Add dem
10+20=30/////ans..


10. A power unit is there by the bank of the river of 750
meters width. A cable is made from power unit to power a
plant opposite to that of the river and 1500mts away from
the power unit. The cost of the cable below water is Rs.
15/- per meter and cost of cable on the bank is Rs.12/- per
meter. Find the total of laying the cable. ans:20250
power unit is in one bank of river…
width of river is 750 m
so the next power plant is on the othr side of river and
1500 m frm dis power plant… ie 750 m frm the opposite bank
so 750*15 + 750*12 ===20250 ///ans


11. The size of a program is N. And the memory occupied by
the program is given by M = square root of 100N. If the size
of the program is increased by 1% then how much memory now
occupied? ans: 0.5%
No mattr watz the value is changed..ex…evn if 100 is changd
to 4000 or anything ..ans is 0.5% .. unless the value of
increase in percentage is 1%..
 

12) How many positive integer solutions does the equation
2x+3y = 100 have? 
ans:16
formula: (constant)/(lcm of two nos)
==100/(2*3)=15.5…(rounded of as 16..)

13) A non-stop bus to Amritsar overtakes an auto also moving
towards
Amritsar at 10 am. The bus reaches Amritsar at 12.30 pm and
starts on the return journey after 1 hr. On the way back it
meets the auto at 2 pm. At what time the auto will reach
Amritsar? ans:3 pm 
This prb requires Logical thinking….wil think ovr it hw to
explain n mail u soon..)) sry fr d delay

14) The total expense of a boarding house is partly fixed
and partly
variable with the number of boarders. The charge is Rs.70
per head when
there are 25 boarders and Rs.60 when there are 50 boarders.
Find the charge per head when there are 100 boarders.  ans:55
equation: x+25y=70*25
          x+50y=60*55   
x-fixed part
y-variable part
((refer RS Aggarwal fr further details)

15) In a circular racetrack of length 100 m, three persons
A, B and C start together. A and B start in the same
direction at speeds of 10 m/s and 8 m/s respectively. While
C runs in the opposite at 15 m/s, when will all the three
meet for the first time on the track after the start?   ans:
  aft 100 s           
Hav been told by my seniors to take LCM of 3 nos…but I guess
its wrong…wil tell u latr.

16) There are 5 distinct pairs of white socks and 5 pairs of
black socks in a cupboard. In the dark, how many socks do I
have to pull out to ensure that I have at least 1 correct
pair of white socks?  ans:6 pairs or 12 socks
Think…if der r 5 pairs of white socks and 5 pairs of black
socks..
If u wanna tak a white socks… the extreme condition is u wil
b picking up atleast 6 pairs…so dat evn though 5 pairs u hav
takn r black  the remaining ONE is white.. SO U NEED TO TAK
ATMOST 6 PAIRS OF SOCKS///

17) Two oranges, 3 bananas and 4 apples cost Rs.15. 3
oranges, 2 bananas and 1 apple cost Rs.10. I bought 3
oranges, 3 bananas and 3 apples. How much did I pay?  ans:15
EQUATION:
 2x+3y+4z=15
 3x+2y+1z=10
Add both equations..
U get…5x+5y+5z=25//ie (5 oranges+ 5 bana+5appl cost 25)
1oran+1 bana+1 app cost =Rs5
3oran+3 bana+3app cost =Rs5*3==15////ans


18) A traveler walks a certain distance. Had he gone half a
kilometer an hour faster \, he would have walked it in 4/5
of the time, and had he gone half a Kilometer an hour
slower, he would have walked 2 ½ hr longer. What is the
distance?  ans:15kms
Dis s data insuffiency ques,,,


19) A student's grade in a course is determined by 6 quizzes
and one
examination. If the examination counts thrice as much as
each of the
quizzes, what fraction of final grade is determined by the
examination? 
ans:1/3
1examnation==3 quizes
Ie 6 quizes=2exams

The ratio 6 quizzes and 1 exam can b re-writtn as 
          2exam(6quizzes) and    1 exam

So exam takes 1/3 part of the final exam….///ans  

20) The value of  ¾ + 5 / 36 + 7 / 144 + …….+17 / 5184 + 19
/ 8100 ans:0.99
formula
1-(last term)

Ie  1-(19/8100)=0.99  ///ans

22) The cost of one pencil, two pens and four erasers is
Rs.22 while the cost of five pencils, four pens and two
erasers is Rs.32.How much will three pencils, three pens and
three erasers cost? Ans 27

1 pencil+2 pens+4 erasers=22
5 pencls+4 pens+2 Erasers=32

Adding dem

6 pencls+6 pens+6Erasers=54

1pencls+1 pens+1Erasers=54/6=9

3 pencls+3 pens+ 3Erasers=27