Q. In a certain city, the probability of a person being a smoker is 0.3. If two people are selected at random, what is the probability that both are smokers?
A.0.09
B.0.21
C.0.3
D.0.6
Solution
The probability that both are smokers is 0.3 * 0.3 = 0.09.
Q. In a certain company, the ratio of the number of engineers to the number of managers is 5:2. If there are 70 engineers, how many managers are there?
A.28
B.30
C.35
D.40
Solution
Let the number of managers be x. According to the ratio, 5/2 = 70/x. Cross-multiplying gives 5x = 140, so x = 28.
Q. In a certain game, the probability of winning is 0.3. If a player plays the game 5 times, what is the probability of winning at least once?
A.0.163
B.0.836
C.0.5
D.0.7
Solution
The probability of losing all 5 games is (1 - 0.3)^5 = 0.168. Therefore, the probability of winning at least once is 1 - 0.168 = 0.832, which rounds to 0.836.
Q. In a certain mixture, the ratio of sugar to water is 1:4. If 2 liters of sugar is added to the mixture, what will be the new ratio of sugar to water if the initial amount of water was 16 liters?
A.1:4
B.1:5
C.1:6
D.1:8
Solution
Initial sugar = 1 liter, water = 16 liters. After adding 2 liters of sugar, the new ratio is 3:16, which simplifies to 1:5.
Q. In a certain mixture, the ratio of sugar to water is 1:4. If 2 liters of sugar is added to the mixture, what will be the new ratio of sugar to water?
A.1:3
B.1:4
C.1:5
D.1:6
Solution
Let the initial amount of sugar be x liters and water be 4x liters. After adding 2 liters of sugar, the new ratio becomes (x + 2) : 4x.
Q. In a certain mixture, the ratio of sugar to water is 1:4. If 2 liters of sugar is added, what will be the new ratio if the total volume of the mixture is 10 liters?
A.1:3
B.1:2
C.1:4
D.1:5
Solution
Initial sugar = 1 part, water = 4 parts. Total = 5 parts. New sugar = 2 liters, water = 8 liters. Ratio = 2:8 = 1:4.
Q. In a certain mixture, the ratio of sugar to water is 1:4. If 2 liters of sugar is added, what will be the new ratio if the total volume of the mixture is 20 liters?
A.1:3
B.1:4
C.1:5
D.1:6
Solution
Initially, there is 1 part sugar and 4 parts water, totaling 5 parts. In 20 liters, there are 4 liters of sugar and 16 liters of water. After adding 2 liters of sugar, the new ratio is 6:16, which simplifies to 1:5.