1.
A shopkeeper earns a profit of 12% on selling a book at 10% discount on the printed price. The ratio of the cost price to the printed price of the book is—
Correct Answer
D. 45 : 56
Explanation
The shopkeeper sells the book at a discount of 10%, which means he sells it for 90% of the printed price. He earns a profit of 12% on this selling price. Let's assume the cost price of the book is 100. The selling price will be 90% of 100, which is 90. The profit earned is 12% of 90, which is 10.8. So, the selling price is 90 + 10.8 = 100.8. The ratio of the cost price to the printed price is 100:100.8, which simplifies to 45:56.
2.
X and Y can do a piece of work in 20 days and 12 days respectively. X started the work alone and then after 4 days Y joined him till the completion of the work. How long did the work last?
Correct Answer
B. 10 days
Explanation
X can do 1/20th of the work in a day and Y can do 1/12th of the work in a day. X worked alone for 4 days, so he completed 4/20th of the work. After that, both X and Y worked together. In one day, they can complete (1/20 + 1/12) of the work, which is (8/240 + 20/240) = 28/240th of the work. To find out how many days it took for them to complete the remaining work, we can set up the equation (28/240) * d = (240 - 4)/240, where d is the number of days. Solving this equation, we find that d = 10 days, which is the answer.
3.
Two dice are tossed. The probability that the total score is a prime number is:
Correct Answer
B. 5/12
Explanation
When two dice are tossed, there are a total of 36 possible outcomes (6 outcomes for each dice). To find the probability of getting a prime number as the total score, we need to determine the number of favorable outcomes. The prime numbers that can be obtained as the sum of two dice are 2, 3, 5, 7, 11. Out of these, only 5 and 11 are possible sums when two dice are thrown. Therefore, there are 6 favorable outcomes (5+6, 6+5, 4+6, 6+4, 5+6, 6+5). Hence, the probability is 6/36, which simplifies to 1/6. However, this is not one of the given answer choices. Therefore, the correct answer cannot be determined based on the information provided.
4.
What should come in place of both x in the equation
Correct Answer
A. 12
Explanation
In the given equation, the numbers 12, 14, 144, and 196 are listed. The pattern between these numbers is that each number is a perfect square. The square root of 144 is 12, and the square root of 196 is 14. Therefore, it can be inferred that the missing values in the equation should also be the square roots of the given numbers. Hence, the missing values should be 12.
5.
Correct Answer
C. .9
6.
What decimal of an hour is a second ?
Correct Answer
B. .00027
Explanation
A second is a unit of time that is equal to 1/60th of a minute or 1/3600th of an hour. To find the decimal of an hour that a second represents, we need to divide 1 by 3600 (the number of seconds in an hour). This calculation gives us 0.00027777778, which can be rounded to 0.00027. Therefore, the correct answer is .00027.
7.
Two trains 140 m and 160 m long run at the speed of 60 km/hr and 40 km/hr respectively in opposite directions on parallel tracks. The time (in seconds) which they take to cross each other, is:
Correct Answer
D. 10.8
Explanation
When two trains are moving in opposite directions, the total distance they have to cover to cross each other is equal to the sum of their lengths. In this case, the total distance is 140m + 160m = 300m.
To find the time it takes for them to cross each other, we need to convert their speeds from km/hr to m/s.
The speed of the first train is 60 km/hr, which is equal to (60 * 1000) / 3600 = 16.67 m/s.
The speed of the second train is 40 km/hr, which is equal to (40 * 1000) / 3600 = 11.11 m/s.
Now, we can calculate the time using the formula: time = distance / relative speed.
The relative speed of the two trains is the sum of their speeds, which is 16.67 m/s + 11.11 m/s = 27.78 m/s.
Therefore, the time it takes for the trains to cross each other is 300m / 27.78 m/s = 10.8 seconds.
8.
Two trains are running in opposite directions with the same speed. If the length of each train is 120 metres and they cross each other in 12 seconds, then the speed of each train (in km/hr) is:
Correct Answer
C. 36
Explanation
The length of both trains combined is 240 meters (120 meters + 120 meters). They cross each other in 12 seconds, so their relative speed is 240 meters / 12 seconds = 20 meters per second. To convert this to kilometers per hour, we multiply by 3.6 (since there are 3600 seconds in an hour and 1000 meters in a kilometer). Therefore, the speed of each train is 20 meters per second * 3.6 = 72 kilometers per hour.
9.
A man can row three-quarters of a kilometer against the stream in minutes and down the stream in minutes. The speed (in km/hr.) of the man in still water is:
Correct Answer
D. 5
Explanation
The speed of the man in still water can be calculated by finding the average of the speed against the stream and the speed down the stream. Since the man takes 2 minutes to row three-quarters of a kilometer against the stream and the same distance down the stream, the speed against the stream is 3/4 km in 2 minutes, or 3/8 km/min. The speed down the stream is also 3/4 km in 2 minutes, or 3/8 km/min. To convert this to km/hr, we multiply by 60, giving a speed of 22.5 km/hr. Therefore, the speed of the man in still water is 22.5/2 = 11.25 km/hr, which can be approximated to 11 km/hr.
10.
In a two-digit, if it is known that its unit's digit exceeds its ten's digit by 2 and that the product of the given number and the sum of its digits is equal to 144, then the number is:
Correct Answer
A. 24
Explanation
Let's assume the two-digit number is represented as AB, where A is the tens digit and B is the units digit. According to the given information, B = A + 2. The product of the number AB and the sum of its digits (A + B) is equal to 144. Substituting B = A + 2, we get AB(A + B) = 144. By trying different values for A and B, we find that A = 2 and B = 4 satisfy the equation. Therefore, the number is 24.