Q2. There are 50 boxes and 50 persons. Person 1 keeps 1 marble in every box, person 2 keeps 2 marbles in every 2nd box, person 3 keeps 3 marbles in every third box. This process goes on till person 50 keeps 50 marbles in the 50th box. Find the total number of marbles kept in the 50th box.
Q3. Mohan gets 3 marks for each correct sum and loses 2 marks for each wrong sum. He attempts 30 sums and obtains 40 marks. The number of sum solved correctly is:
Q5. Two boats A and B start towards each other from two places, 108 km apart. Speed of the boat A and B in still water are 12 km/hr and 15 km/hr respectively. If A proceeds down and B up the stream, they will meet after.
(a) 4.5 hours
(d) 6 hours
Q6. The speed of the current is 5 km/hour. A motorboat goes 10 km upstream and back again to the starting point in 50 minutes. The speed (in km/hour) of the motorboat in still water is:
Q7. A can do a piece of work in 70 days and B is 40% more efficient than A. Then the number of days taken by B to do the same work is
(a) 40 days
(b) 60 days
(c) 50 days
(d) 45 days
Q8. Some persons can do a piece of work in 12 days. Two times the number of such persons will do half of the work in
(a) 9 days
Q9. If 4 men or 6 women can do a piece of work in 12 days working 7 hours a day; how many days will it take to complete a work twice as large with 10 men and 3 women working together 8 hours a day?
(a) 6 days
Q10. 15 men take 20 days to complete a job working 8 hours a day. The number of hours a day should 20 men take to complete the job in 12 days.
(a) 5 hours
(b) 10 hours
(c) 15 hours
(d) 18 hours
Q11. In what time will Rs. 8000, at 3% per annum, produce the same interest as Rs. 6000 does in 5 years at 4% simple interest is?
(a) 5 years
(b) 6 years
(c) 3 years
(d) 4 years
Q12. A sum of Rs. 800 amounts to Rs. 920 in 3 years at the simple interest rate. If the rate is increased by 3% p.a. what will be the sum amount to in the same period?
(a) Rs. 992
(b) Rs. 962
(c) Rs. 942
(d) Rs. 982
Q13. The simple interest on a sum of money is 8/25 of the sum. If the number of years is numerically half the rate percent per annum, then the rate percent per annum is
(c) 6 1/4
Q14. A company offers three types of successive discounts:
(i) 25% and 15%
(ii) 30% and 10%
(iii) 35% and 5%, which offer is the best for a customer?
(a) First offer
(b) Second offer
(c) Third offer
(d) Any one: all are equally good
Q15. An article is listed at Rs. 900 and two successive discounts of 8% and 8% are given on it. How much would the seller gain or loss, if he gives a single discount of 16% instead of two discounts?
(a) Gain of Rs. 4.76
(b) Loss of Rs. 5.76
(c) Gain of Rs. 5.76
(d) Loss of Rs. 4.76
Sol. Marble in the 50th box will be kept by 1st, 2nd, 5th, 10th, 25th and 50th person is a factor of 50.
Number of marbles = 1 + 2 + 5 + 10 + 25 + 50 = 93
Sol. Let time = t years
According to question,
(8000 × 3 × t)/100=(6000 × 5 × 4)/100
240 t = 1200
t = 5 years
Hence required time = 5 years
Sol. For detailed explanation of such type of questions follow the solution of previous question.
Hence, increased amount =(800 × 9)/100
= Rs. 72
Total amount = (920 + 72) = Rs. 992
Sol. (i) 25% and 15%
(ii) 30% and 10%
(iii) 35% and 5%
3rd offers is the best for customer