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Important Questions of Maths For DSSSB Exams

Important Questions of Maths For DSSSB Exams_30.1

Q1. Sum of cost price of two watches is Rs 3360. One watch is sold at a profit of 12% and other at a loss of 12%. Due to this transaction, there is neither profit nor loss. Find the cost price of each watch. 
(a) Rs 1680, Rs 1680
(b) Rs 1280, Rs 1280
(c) Rs 1000, Rs 1000
(d) Rs 2100, Rs 2160

Q2. A seller buys 50 kg oranges for Rs 525 and gains a profit equal to the cost price of 10 kg of oranges. Find the selling price per kg of oranges (Rs/kg). 
(a) 12.60
(b) 11.60
(c) 10.20
(d) 12

Q3. Find a number, one-seventh of which exceeds its eleventh part by 100. 
(a) 1925
(b) 1825
(c) 1540
(d) 1340

Q4. 6 bells commence tolling together and toll of intervals are 2, 4, 6, 8, 10 and 12 s, respectively. In one hour, how many times do they toll together? 
(a) 16
(b) 32
(c) 21
(d) 31

Q5.  A certain type of board is sold in lengths of multiples of 2 ft. the shortest board sold is 6 ft and the longest is 24 ft. A builder needs a large quantity of these types of board in 5 1/2 ft lengths. Find the length of be ordered for which waste is minimum.  
(a) 24 ft
(b) 26 ft
(c) 22 ft
(d) 52 ft

Q6. Salaries of Ravi and Sumit are in the ratio 2 : 3. If the salary of each is increased by Rs. 4000, the new ratio becomes 40 : 57. What is Sumit’s present salary?
(a) Rs. 20,000  
(b) Rs, 30,000
(c) Rs, 38,000  
(d) Rs.45, 000

Q7. The ratio between the rates of walking of A and B is 3:4 . If the time taken by B to cover a certain is 48 minutes, the time taken (in minutes) by A to cover that distance is :
(a) 36
(b) 64
(c) 21(5/7)
(d) 27(3/7)

Q8. A fruit seller buys mangoes at the rate of 15 for 12 and sells them at the rate of 15 per dozen. Find his gain percentage.
(a) 25.65% 
(b) 32.25%
(c) 51.35% 
(d) 56.25%

Q9. Summer started cycling along the boundaries of a square field from corner point A. After half an hour he reached the corner point C, diagonally opposite of A. If his speed was 8 kmph, what is the area of the field in sq. km?
(a) 64   
(b) 8   
(c) 4   
(d) None of these

Q10.  A man riding a cycle at 12 km/hr can reach a village in 4(1/2) hours. If he is delayed by   1(1/2 ) hours at the start, then in order to reach his destination in time, he should ride with a speed of:
(a) 15 km/hr  
(b) 16 km/hr  
(c) 18 km/hr  
(d) 20 km/hr
Solutions

S1. Ans.(a) 
Sol.
On one watch, he earns 12% profit and on the other one 12% loss. There is, finally, no profit no loss.
Hence CPs of both the watches should be same such that their summation = Rs 3360. 
Hence CP/watch = (Rs.3360)/2 = Rs. 1680
Hence option (a) is the answer.  

S2. Ans.(a)
Sol. 
Assume SP/kg = Rs x/kg.
CP/kg =(Rs.525)/50 = Rs. 10.5/kg
Total SP – Total CP = profit ⇒ 50x – Rs. 525 = 10 × Rs. 10.5 = Rs. 105
Or, 50x = Rs. 105 + Rs. 525 = Rs. 630
Hence x =(Rs.630)/50 = Rs. 12.6/kg

S3. Ans.(a)
Sol.
Let the number be x.
x/7- x/11 = 100
(11x-7x)/ (11 x 7)=100
4x = 77 x 100
x = 1925 

S4. Ans.(d)
Sol. 
LCM of 2, 4, 6, 8, 10, 12 = (2 × 2 × 3 × 2 × 5) = 120
∴ After every 2 min they toll together
∴ Number of times they toll together in one hour
=(60/2+1) times = 31 times

S5. Ans.(c)
Sol. 
LCM of (2 and 5 1/2) = LCM of (2 and 11/2)
Required answer = (LCM of 2 and 11)/(HCF of 1 and 2)=22/1 = 22 ft  

S6. Ans.(c)
Sol. 
Let the original salaries of Ravi and Sumit be Rs. 2x and Rs. 3x respectively.
Then, (2x + 4000)/ (3x + 4000)= 40/57
57(2x + 4000) = 40(3x + 4000)
6x = 68,000
3x = 34,000
Sumit’s present salary = (3x + 4000) = Rs. (34000+ 4000) = Rs. 38,000

S7. Ans.(b) 
Sol.
Ratio of time taken = 1/3 : 1/4 = 4:3
If B takes 3 min ,A takes 4 min
If B takes 48 min ,A takes (4/3 × 48)min = 64 minutes

S8. Ans.(d)
Sol. 
C.P. of one mango = 12/15 = 80 paise ; S.P. of one mango = 15/12=Rs 1.25 
Gain = 45 paise , gain = 45/80 × 100 = 56.25 %

S9. Ans.(c)
Sol. 
Distance covered in half an hour = 4 km.
2× side of the square = 4 km 
side of square = 2 km
So Area of the field = 4 sq.km.

S10. Ans.(c)
Sol. 
Distance = (Speed× Time)= (12× 9/12) km = 54 km
Now, distance = 54 km and time taken = 3 hrs.
so speed = distance/time = 54/3 = 18 km/hr.