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Maths Questions for DSSSB Exam 2017 (Solutions)

Maths Questions for DSSSB Exam 2017 (Solutions)_30.1
Q1. If the successive discount be 25%,30% and 40% then what will be the single equivalent discount?
(a)65%
(b)68.5%
(c)72.4%
(d)66.5%
Q2. Ravi goes to a place on bicycle at speed of 22 kmph and comes back at a speed of 20 kmph. If the time taken by him in second case is 36 min. more than that of first case, what is the total distance travelled by him(in km)?
(a)128
(b)136
(c)123
(d)132
Q3. The average of sixty observations was calculated as 30. It was found later, that 45 and 46 of the observation were misread as 54 and 64 respectively. What is the correct average?
(a)26.7
(b)34.25
(c)29.55
(d)32.55
Q4. A man swimming in a stream which flows 2.5 kmph finds that in a given time he can swim thrice as far with the stream as he can against it. How many distance he will cover in 4 hours against the current?
(a)10 km
(b)14 km
(c)8 km
(d)9 km
Q5. Two barrels contain a mixture of petrol and diesel. The content of petrol is 40% in the first barrel and 70% in the second barrel. In what ratio must the mixtures from the first and the second barrels be taken to form a mixture containing 55% diesel?
(a)1 : 5
(b)5 : 1
(c)3 : 2
(d)5 : 3
Q6. If the compound interest accrued on an amount of Rs. 12,500 in 2 yr is Rs. 15,625, what is the rate of interest per cent per annum?
(a) 60
(b) 45
(c) 50
(d) 40
Q7. In how many different ways can 5 boys and 4 girls be arranged in a row such that all the boys stand together and all the girls stand together?
(a) 7,500
(b) 5,760
(c) 5,670
(d) 7,560
Q8. The average of the ages of 4 friends is 24. Even if the age of the 5th friends is added the average remains 24. What is the age of the 5th friend?
(a) 23 yr
(b) 21 yr
(c) 24 yr
(d) Cannot be determined
Q9. 9 men working for 8 h a day complete a piece of work in 15 days. In how many days can 6 men working for 15 h a day complete the same piece of work?
(a) 21
(b) 12
(c) 14
(d) 20
Q10. The total area of a circle and a rectangle is equal to 586 sq cm. The diameter of the circle is 14 cm. What is the sum of the circumference of the circle and the perimeter of the rectangle if the length of the rectangle is 24 cm?
(a) 128 cm
(b) 130 cm
(c) 134 cm
(d) 132 cm
Solutions:
S1. Ans.(b)
Sol.
Let equivalent discount be x%
∴(100-x)/100=75/100×70/100×60/100
⇒ 100 – x = 31.5
⇒ x = 68.5%
S2. Ans.(d)
Sol.
Let distance = d km
∴d/20=d/22+3/5
⇒ d = 132 km
S3. Ans.(c)
Sol.
Correct average
=(60×30-(54+64)+45+46)/60
= 29.55
S4. Ans.(a)
Sol.
Let speed of man = x kmph
∴ (x + 2.5) = 3 (x -2.5)
⇒ 2x = 10
⇒ x = 5 kmph
∴ Required distance = (5 – 2.5)×4
= 10 km
Maths Questions for DSSSB Exam 2017 (Solutions)_40.1
S6. Ans.(c)
Sol.
Let rate of interest = r% per annum
∴ 15,625 = 12,500 [(1+r/100)^2-1]
⇒(1+r/100)^2=2.25
⇒1+r/100=15/10
⇒ r = 50%
S7. Ans.(b)
Sol.
Total ways = 5! × 4! × 2!
= 5,760
S8. Ans.(c)
Sol.
Age of 5th friend = 5 × 24 – 4 × 24
= 24 years
S9. Ans.(b)
Sol.
Required no. of men
=(9×8×15)/(6×15)
= 12
S10. Ans.(a)
Sol.
Let breadth of rectangle = b cm
∴22/7×7×7+24b=586
⇒ b= 18 cm
∴ Required answer =2×22/7×7+2(24+18)
= 128 cm