Answer: B) 6 kmph Explanation: Speed of the stream = 1Motor boat speed in still water be = x kmphDown Stream = x + 1 kmphUp Stream = x - 1 kmph[35/(x + 1)] + [35/(x - 1)] = 12x = 6 kmph

Answer: C) 2/21 Explanation: Given that there are three blue marbles, four red marbles, six green marbles and two yellow marbles.   Probability that both marbles are blue = ³C₂/¹⁵C₂ = (3 x 2)/(15 x 14) = 1/35 Probability that both are yellow = ²C₂/¹⁵C₂ = (2 x 1)/(15 x 14) = 1/105 Probability that one blue and other is yellow = (³C₁ x ²C₁)/¹⁵C₂ = (2 x 3 x 2)/(15 x 14) = 2/35   Required probability = 1/35 + 1/105 + 2/35 = 3/35 + 1/105 = 1/35(3 + 1/3) = 10/(3 x 35) = 2/21

Answer: A) 26 July Explanation:

Answer: A) 9 Explanation: Speed in still water = Average of Speed in Upstream and speed in Downstream = 1/2 (12 + 6) kmph = 9 kmph.

Answer: D) 2 hrs Explanation: Speed in downstream = 96/8 = 12 kmph Speed of current = 4 km/hr Speed of the boatman in still water = 12 – 4 = 8 kmph Speed in upstream = 8 – 4 = 4 kmph Time taken to cover 8 km upstream = 8/4 = 2 hours.

Answer: D) 20 years Explanation: Present total age of the members = 26(5) = 130 years.   Present age of the youngest member = 10 years   Present total age of the remaining four members = 130 -10 = 120 years   Their average age at the time of the birth of the youngest member = 120-4×104 = 30 - 10 = 20 years.

Answer: C) Over Haeat Explanation: The slot covers on a computer reduce the dust build up inside the computer. So the slot covers should be present in proper place.The missing covers can disrupt the airflow design of the case and cause overheating problems.

Answer: C) Larva Explanation: A Bill becomes a Law; a Larva becomes an insect. (Or) A Bill turns into a law; a Larva turns into an Insect.