Q. A family has 2 children. What is the probability that both children are boys if it is known that at least one is a boy?
A.1/2
B.1/3
C.1/4
D.1/5
Solution
The possible combinations of children are BB, BG, GB, GG. Given that at least one is a boy, we can eliminate GG, leaving us with BB, BG, GB. Out of these 3 combinations, only 1 is BB. Therefore, the probability is 1/3.
Q. A family has 3 children. What is the probability that at least one child is a girl given that at least one child is a boy?
A.1/2
B.2/3
C.3/4
D.1/4
Solution
The only combinations with at least one boy are: BBB, BBG, BGB, GBB, BGG, GBG, GGB. Out of these, all combinations except BBB have at least one girl. Thus, P(At least one girl | At least one boy) = 6/7.
Q. A kite is flying at a height of 100 m. If the angle of elevation from a point on the ground to the kite is 30 degrees, how far is the point from the base of the kite?
A.100 m
B.200 m
C.300 m
D.400 m
Solution
Using tan(30°) = height/distance, we have 1/√3 = 100/distance. Therefore, distance = 100√3 ≈ 173.2 m.
Q. A kite is flying at a height of 100 meters. If the angle of depression from the kite to a point on the ground is 30 degrees, how far is the point from the point directly below the kite?
A.50 m
B.60 m
C.70 m
D.80 m
Solution
Using tan(30°) = 100/distance, we have 1/√3 = 100/distance. Therefore, distance = 100√3 ≈ 173.21 m.
Q. A kite is flying at a height of 30 m. If the angle of elevation from a point on the ground to the kite is 60 degrees, how far is the point from the base of the kite?
A.15√3 m
B.30 m
C.10√3 m
D.20 m
Solution
Using tan(60°) = height/distance, we have distance = height/tan(60°) = 30/√3 = 15√3 m.
Q. A kite is flying at a height of 30 meters. If the angle of elevation from a point on the ground to the kite is 45 degrees, how far is the point from the base of the kite?
A.15 m
B.30 m
C.45 m
D.60 m
Solution
Using tan(45°) = height/distance, we have 1 = 30/distance. Therefore, distance = 30 m.
Q. A kite is flying at a height of 50 meters. If the angle of elevation from a point on the ground to the kite is 30 degrees, how far is the point from the base of the kite?
Q. A ladder is leaning against a wall. The foot of the ladder is 12 meters away from the wall, and the angle between the ladder and the ground is 60 degrees. What is the height at which the ladder touches the wall?
A.12√3 m
B.6 m
C.12 m
D.24 m
Solution
Using sin(60°) = height/hypotenuse, we find the height = 12 * tan(60°) = 12√3 m.
Q. A man is standing 100 meters away from a building. If the angle of elevation to the top of the building is 45 degrees, what is the height of the building?
A.100 m
B.50 m
C.75 m
D.25 m
Solution
Using tan(45°) = height/distance, we have height = distance * tan(45°) = 100 * 1 = 100 m.