Test-Series - numerical

Test Number 9/39

Q: 50 men took a dip in a water tank 40 m long and 20 m broad on a religious day. If the average displacement of water by a man is 4 cu.m , then the rise in the water level in the tank will be:
A. 20 cm
B. 25 cm
C. 50 cm
D. 35 cm
Solution: Total volume of water displaced =(4 x 50) cu.m = 200 cu.m   Rise in water level = 20040×20=0.25m = 25cm
The correct answer is: B) 25 cm
Q: The product of two numbers is 4107. If the H.C.F of these numbers is 37, then the greater number is 
A. 185
B. 107
C. 101
D. 111
Solution: Let the numbers be 37a and 37b. Then , 37a x 37b =4107  => ab = 3.  Now co-primes with product 3 are (1,3)  So, the required numbers are (37 x 1, 37 x 3) i.e, (37,111).  Therefore, Greater number = 111.
The correct answer is: C) 111
Q: The cost of Type 1 rice is Rs. 15 per kg and Type 2 rice is Rs.20 per kg. If both Type 1 and Type 2 are mixed in the ratio of 2 : 3, then the price per kg of the mixed variety of rice is
A. Rs. 18.50
B. Rs. 19
C. Rs. 18
D. Rs. 19.50
Solution: Let the price of the mixed variety be Rs. x per kg. By the rule of alligation, we have :   Cost of 1 kg of type 1 rice           Cost of 1 kg of type 2 rice           ∴(20-x)/(x-15) = 2/3  ⇒ 60 - 3x = 2x - 30  ⇒ x = 18.
The correct answer is: C) Rs. 18
Q: A man sitting in a train which is traveling at 50 kmph observes that a goods train, traveling in opposite direction, takes 9 seconds to pass him. If the goods train is 280 m long, find its speed.?

A. 60
B. 64
C. 62
D. 65
Solution: Relative speed =280/9  m / sec = (280/9*18/5)  kmph = 112 kmph.   Speed of goods train = (112 - 50) kmph = 62 kmph.
The correct answer is: B) 62
Q: A can contains a mixture of two liquids A and B in the ratio  7 : 5. When 9 litres of mixture are drawn off and the can is filled with B, the ratio of A and B becomes 7 : 9. How many litres of liquid A was contained by the can initially?
A. 21
B. 20
C. 25
D. 10
Solution: Suppose the can initially contains 7x and 5x litres of mixtures A and B respectively   Quantity of A in mixture left =7x-712×9=7x-214 litres.   Quantity of B in mixture left =  5x-512×9=5x-154litres.   7x-2145x-154+9=79   ⇒28x-2120x+21=79   ⇒x=3  So, the can contained 21 litres of A.
The correct answer is: C) 21
Q: Three unbiased coins are tossed.What is the probability of getting at least 2 heads? . Let E = event of getting at least two heads = {THH, HTH, HHT, HHH}. P(E) = n(E) / n(S)       = 4/8= 1/2 }
A. 1/4
B. 3/4
C. 1/2
D. 1/3
Solution: Here S= {TTT, TTH, THT, HTT, THH, HTH, HHT, HHH
The correct answer is: B) 1/2
Q: A tank is 25m long 12m wide and 6m deep. The cost of plastering its walls and bottom at 75 paise per sq m is
A. Rs. 458
B. Rs. 358
C. Rs. 258
D. Rs. 558
Solution: Area to be plastered = 2l+b×h+l×b  =225+12×6+25×12=744sq.m  Cost of plastering = 744×75100=Rs.558                       
The correct answer is: D) Rs. 558
Q: A parallelogram has sides 30m and 14m and one of its diagonals is 40m long. Then its area is
A. 136
B. 236
C. 436
D. 336
Solution: let ABCD be the given parallelogram  area of parallelogram ABCD = 2 x (area of triangle ABC)  now a = 30m, b = 14m and c = 40m  s=1/2 x (30+14+40) = 42    Area of triangle ABC = ss-as-bs-c     = 4212282= 168sq m  area of parallelogram ABCD = 2 x 168 = 336 sq m
The correct answer is: C) 336
Q: A certain sum of money amounts to Rs 1008 in 2 years and to Rs 1164 in 3 ½  years. Find the sum and the rate of interest.
A. 800, 14%
B. 800, 12%
C. 800, 19%
D. 800, 13%
Solution: S.I. for 1 ½ years = Rs (1164 - 1008) = Rs 156 .  S.I. for 2 years = Rs (156 x 23 x 2)= Rs 208.  Therefore, Principal = Rs (1008 - 208) = Rs 800.  Now, P = 800, T= 2 and S.I. = 208. Therefore, Rate = (100 x S.I.) / (P x T) = [ (100 x 208)/(800 x 2)]% = 13%
The correct answer is: B) 800, 13%
Q: Product of two co-prime numbers is 117. Their L.C.M  should be
A. 1
B.  Equal to their H.C.F
C. 117
D. cannot be calculated
Solution: H.C.F of co-prime numbers is 1. So, L.C.M = 117/1 =117
The correct answer is: B) 117

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