100 students appeared for two different examinations 60 passed the first,50 the second and 30 both the examinations.Find the probability that a student selected at random failed in both the examination a)5/6 b)1/5 c)1/7 d)5/7 Solution-60+50-30=80 100-80=20 20/100=1/5. so B is the answer. Q 4. There are 10 points on a straight line AB and 8 on another straight line AC none of them being point A. how many triangles can be formed with these points as vertices? Option a. 680 b. 720 c. 816 d. 640 Solution
100 students appeared for two different examinations 60 passed the first,50
the second and 30 both the examinations.Find the probability that a student
selected at random failed in both the examination
a)5/6
b)1/5
c)1/7
d)5/7
Solution-60+50-30=80
100-80=20
20/100=1/5.
so B is the answer.
Q 4. There are 10 points on a straight line AB and 8 on another straight line AC
none of them being point A. how many triangles can be formed with these points
as vertices?
Option
a. 680
b. 720
c. 816
d. 640
Solution
To form a triangle we need 3 points
select 2 points from the 10 points of line AB & 1 from the 8 on AC
= (10C2)*(8C1)
select 2 points from the 8 points of line AC & 1 from the 10 on AB=
(8C2)*(10C1)
total no. of triangles = (10C2)*(8C1)+ (8C2)*(10C1) = 640
d.640
Q 5. From a bag containing 8 green and 5 red balls,three are drawn one after the
other .the probability of all three balls beings green if the balls drawn are replace
before the next ball pick and the balls drawn are not replaced , are respectively.
a)512/2197,336/2197
b) 512/2197,336/1716
c) 336/2197,512/2197
d) 336/1716,512/1716
Solution-THE PROBABILITIES OF GETTING WITH REPLACEMENT
IS=8/13*8/13*8/13=512/2197
THE PROBABILITIES OF GETTING WITHOUT REPLACEMENT
=8/13*7/12*6/11=336/2197
Q 6. find the greatest number that will divide 148 246 and 623 leaving remainders
4 6 and 11 respectively.
a) 20 b) 12 c)6 d)48
Solution-Hcf ( (148-4), (246-6), (623-11))=12
Q 7. a mother her little daughter and her just born infant boy together stood on a
weighing machine which shows 74kgs.how much does the daughter weigh if the
mother weighs 46kg more than the combined weight of daughter and the infant
and the infant weighs 60% less than the daughter.
a)9
b)11
c)cannot be determined
d)10
Solution-daughter weight is x
infant weight is 60% less than daughter i.e., 0.4x
mother weight is (x+0.4x+46)
total weight = x + 0.4x + (x+0.4X+46) = 74
solving the eq. x = 10
option d is correct
Q 8. find the number of ways a batsman can score a double century only in terms
of 4's & 6's?
a)15
b)16
c)17
d)18
Solution-4's and 6's
50 0
47 2
44 4
41 6
38 8
35 10
32 12
29 14
26 16
23 18
20 20
17 22
14 24
11 26
8 28
5 30
2 32
So total 17 ways but here it is 4's & 6's both so don't consider 1st one
Final ans : 16 ways
Q 9. 98. Thomas takes 7 days to paint a house completely whereas Raj would
require 9 days to paint the same house completely. How many days will take to
paint the house if both them work together. (Give answers to the nearest
integer)?
A. 4
B. 2
C. 5
D. 3
Solution-work done by thomas in day=1/7
work done by other in a day=1/9
work done by both in a day=1/7 +1/9 =16/63
days required by both = 63/16
Answer-A
Q 10. how many positive integers less than 4300 of digits 0-4.
a) 560 b)565 c)575 d)625
Solution-Ans is 575
one digit no =4 (0 is not a positive integer)
two digit no=4*5=20
three digit no=4*5*5=100
four digit no=3*5*5*5=375(the possibility for 1,2,3 will come in the first
position)four digit no=1*3*5*5(the possibility of 4is fixed in the first position and
then 0,1,2 is comes in second position)and the last digit is 4300 we include this
number also
Ans is 4+20+100+375+75+1=575
Q 11. A person travels from Chennai to Pondicherry in cycle at 7.5 Kmph. Another
person travels the same distance in train at a speed of 30 Kmph and reached 30
mins earlier. Find the distance.
A)5 Km
B)10 Km
C)15km
D)20km
Solution-Let, time taken by ϲ =t
//ly, time taken by train ω =t-30
We know that.....speed=distance /time
Speed of bicycle ϲ, 7.5=d/t....(1)
Speed of ω, 30=d/(t-30/60)....(2)
Sol 1&2,we get t=0.666
By sub and value in equal(1)
We d=4.999~5km
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