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Maths Questions for DSSSB Exam (Solutions)

Maths Questions for DSSSB Exam (Solutions)_30.1
Q1.Simple interest on a certain sum at the rate of 16% per annum for 4 years is Rs. 15,360. What is the compound interest at the same sum at the rate of 5% for two years?
(a) Rs 2,460
(b) Rs 2,696
(c) Rs 2,966
(d) Rs 2,669
Q2.In a bag there are three pink and five white balls. Three balls are chosen randomly. What is the probability that at least one is pink and atmost two are white?
(a) 11/28
(b) 23/28
(c) 13/28
(d) 15/28
Q3.A man’s downstream swimming rate is thrice of his upstream swimming rate .The rate of stream is 3 kmph. If he covers 12 km upstream in 2.5 hours, what distance he will cover in 5 hours downstream?
(a) 75 km
(b) 76 km
(c) 70 km
(d) 72 km
Q4.Two trains P and Q are running in opposite direction to each-other. The length of train P is 240 metres and speeds of trains P and Q are 72 kmph and 90 kmph respectively. If trains took 15 seconds to cross each other and train Q crosses a tunnel in 24 seconds, what is the length of the tunnel?
(a) 150 m
(b) 165 m
(c) 200 m
(d) 125 m
Q5.In a 63 litre mixture of milk and water, the ratio of milk to water is 5 : 4 . What amount of milk should be added to this mixture to make the ratio of water to milk 5 : 7 ?
(a) 6.2 li
(b) 5.4 li
(c) 4.2 li
(d) 4.8 li
Q6.CP of 20 article is same as the SP of 15 article, find the profit percentage.
(a) 33 ⅓%
(b) 25%
(c) 20%
(d) 30%
Q7.If the ratio of MP, SP and CP is 5 : 4 : 3. Find the ratio of discount percentage to profit percentage.
(a) 3 : 5
(b) 5 : 3
(c) 3 : 4
(d) 4 : 3
Q8.The ratio of age of mother and that of son at present is 5 : 2 and after 8 year it will be 2 : 1. Find the difference between the present age of mother and that of son.
(a) 24 year
(b) 26 year
(c) 28 year
(d) 25 year
Q9.Three successive discounts of 20%, 25% and 50% are equivalent to single discount of
(a) 70%
(b) 75%
(c) 80%
(d) 50%
Q10.Find the area of the square whose side is equal to the diagonal of a rectangle of length 4 cm and breadth 3 cm.
(a) 25 cm²
(b) 49 cm²
(c) 84 cm²
(d) 100 cm²
Solutions:
S1. Ans.(a)
Sol.
Sum=(15,360×100)/(16×4)
=24,000
∴ CI=24000[(1+5/100)^2–1]
=24000×41/400
=Rs.2,460
Maths Questions for DSSSB Exam (Solutions)_40.1
S3. Ans.(d)
Sol.
Upstream swimming rate of man
=12/2.5
= 4.8 km/hr
∴ Required distance = 3 × 4.8 × 5 = 72 km
S4. Ans.(b)
Sol.
Let length of train Q = x metre
∴ (x + 240) = (72 + 90) × 5/18 × 15
⇒ x = 675 – 240
⇒ x = 435 m
∴ Length of tunnel
=90×24×5/18–435
= 600 – 435
= 165 m
S5. Ans.(c)
Sol.
Initial milk=63×5/9
=35 l
Water=63×4/9
=28 l
Let x ℓ milk is added.
∴ 28/(35+x)=5/7
⇒ x = 21/5
⇒ x = 4.2 li
S6. Ans.(a)
Sol.
Let C.P of 1 article be rupee 1
So, S.P of 1 article = 20/15=4/3
∴Required profit percent=(1/3)/1×100=33 1/3%
OR
[(20 –15)/15]×100
=100/3% 
S7. Ans.(a)
Sol.
MP = 5x
SP = 4x
CP = 3x
∴ Discount Percentage
=((5x –4x)/5x)×100
= 20%
Profit Percentage
=[(4x –3x)/3x]×100
=100/3%
∴ Required ratio=20/(100/3)=3∶5
S8. Ans.(a)
Sol.
Let mother age = 5x
Son age = 2x
Now
(5x+8)/(2x+8)=2/1
5x + 8 = 4x + 16
x = 8
∴ Mother present age = 40 year
Son present age = 16 years
∴ Difference = 40 – 16 =24 year
S9. Ans.(a)
Sol.
Equivalent discount% = [1 –4/5×3/4×1/2]×100
=[1 –3/10]×100
= 70%
S10. Ans.(a)
Sol.
Length = 4 cm
Breadth = 3 cm
∴ Diagonal = √(4^2+3^2 )
Diagonal = 5 cm
∴ side of square = 5 cm
Area of square = (side)²
= (5)²
= 25 cm²