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Maths Questions for DSSSB Exam (Solutions)

Maths Questions for DSSSB Exam (Solutions)_30.1
Q1.In a two digit number the product of digits is 24 and sum of digits is 10. Find the two digit number.
(a) 64
(b) 46
(c) Either 64 or 46
(d) Either 82 or 28
Q2.In a class of 32 students, the average weight of all students is 42 kg . Due to admission of 4 new students in the class the average weight increases by 1 kg . Find the average weight of new students admitted.
(a) 50 kg
(b) 51 kg
(c) 48 kg
(d) 54 kg
Q3.Three persons A, B and C can do a job in 12 days together. If their efficiency of working be in the ratio 2 : 3 : 4, Find in what time B can complete the same work alone ?
(a) 39 days
(b) 36 days
(c) 42 days
(d) 32 days
Q4.What will be the probability of selecting a letter as vowel from the word KNITE ?
(a) 2/5
(b) 4/5
(c) 3/5
(d) 5/7
Q5.In how many ways 32 men can hand shake in a room ?
(a) 502
(b) 694
(c) 496
(d) 486
Q6.A gave a sum of 4500 at simple rate of interest of 12% to B for 4 years and B gave this amount to C at the rate of 10% for 4 years. Find how much extra amount has to be paid by B to A after 4 years ?
(a) Rs. 340
(b) Rs. 360
(c) Rs. 400
(d) Rs. 350
Q7.Three persons P, Q and R started a business by investing their capitals in the ratio of 4 : 5 : 2. After 6 months, P and R invested half more of their initial capital amount . After a year, the total profit was Rs. 12,450. Find the share of Q in the profit.
(a) Rs. 5,020
(b) Rs. 4,880
(c) Rs. 4,910
(d) Rs. 4,980
Q8.A train-A passes a stationary train B and a pole in 24 sec and 9 sec respectively. If the speed of train A is 48 kmph what is be the length of train B ?
(a) 190 m
(b) 160 m
(c) 180 m
(d) 200 m
Q9.The ratio between area of a rectangular field and area of a square field is 3 : 2. If the area of rectangular field is equal to 216 sq.metre, what is the perimeter of the square field ?
(a) 50 m
(b) 45 m
(c) 48 m
(d) 32 m
Q10.Two mixtures A and B have alcohol and water in the ratio of 2 : 3 and 3 : 4 respectively. If 20 litre of mixture A was mixed with 28 litre of mixture B then find the ratio of alcohol to water in resultant mixture.
(a) 5 : 7
(b) 7 : 5
(c) 4 : 5
(d) 16 : 11
Solutions:
S1. Ans.(c)
Sol.
Let no. is 10x + y
∴ xy = 24
and x + y = 10
from these two equations digits are either 6, 4 or 4, 6
∴ No. = 10 × 6 + 4 or 10 × 4 + 6
= 64 or 46
S2. Ans.(b)
Sol.
Required average=(36×43 –32×42)/4
=204/4
=51 kg
S3. Ans.(b)
Sol.
Let their efficiency be 2x, 3x and 4x respectively.
∴ total work = 12 × 9x = 108x
∴ time taken by B to complete the job = 108x/3x = 36 days
S4. Ans.(a)
Sol.
Required probability=2/5
S5. Ans.(c)
Sol.
Required ways = ³²C₂
=(32×31)/2
= 16 × 31
= 496
S6. Ans.(b)
Sol.
Extra sum given by B to A
=(4500×12×4)/100 –(4500×10×4)/100
= 45 × 8
= 360 rupees
S7. Ans.(d)
Sol.
Ratio of their profits
= 4 × 6 + 6 × 6 : 5 × 12 : 2 × 6 + 3 × 6 
= 2 : 2 : 1
∴ Q’s share=2/5×12,450
= 2 × 2490
= Rs. 4,980 
S8. Ans.(d)
Sol.
Length of train A=48×9×5/18
=120 m
∴ Length of train B
=48×24×5/18–120
= 320 – 120
= 200 m
S9. Ans.(c)
Sol.
Area of square field = a²
=2/3×216
= 144 sq. m.
∴ a = 12 m
∴ Required perimeter = 48 m
S10. Ans.(a)
Sol.
Required ratio=(2/5×20+3/7×28)/(3/5×20+4/7×28)
=20/28
=5/7