Answer: D) 117 days Explanation: K's work in a day(1st day) = 1/30L's work in a day(2nd day)= -1/60(demolishing)hence in 2 days, combined work= 1/30 - 1/60 =1/60since both works alternatively, K will work in odd days and L will work in even days.1/60 unit work is done in 2 days58/60 unit work will be done in 2 x 58 days = 116 daysRemaining work = 1-58/60 = 1/30Next day, it will be K's turn and K will finish the remaining 1/30 work.hence total days = 116 + 1 = 117.

Answer: A) 72 km Explanation: Rate of her upstream = 12/2.5 = 4.8 km/hr Then, ATQ Rate of downstream = 4.8 x 3 = 14.4 km/hr   Hence, the distance she covers downstream in 5 hrs = 14.4 x 5 = 72 kms.

Answer: D) 253 Explanation: The first person shakes hands with 22 different people, the second person also shakes hands with 22 different people, but one of those handshakes was counted in the 22 for the first person, so the second person actually shakes hands with 21 new people. The third person, 20 people, and so on... So, 22 + 21 + 20 + 19 + 18 + 17 + 16 + 15 + 14 + 13 + 12 + 11 + 10 + 9 + 8 + 7 + 6 + 5 + 4 + 3 + 2 + 1= n(n+1)/2 = 22 x 23 /2 = 11 x 23 = 253.

Answer: B) 15 Explanation: Given when she sells at Rs. 160 for 20 articles, she get 40% loss.   Then, to get 20% profit selling at Rs. 240 for let 'P' articles   => 1602060=240p120   => 120 x 160 x P = 20 x 70 x 240   => P =  15 articles.

Answer: D) 5 minutes Explanation: Let the total capacity of tank be 90 liters.Capacity of tank filled in 1 minute by K = 3 liters.Capacity of tank filled in 1 minute by L = 15 liters.Therefore, capacity of the tank filled by both K and L in 1 minute = 18 liters.Hence, time taken by both the pipes to overflow the tank = 90/18 = 5 minutes.

Answer: C) 3 hrs 30 min Explanation: Let the speed of boat and stream be x and y kmph respectively. According to question d/x+y + d/x-y = 5h 15m or 21/4 hrs ......(i) and 2d/x-y = 7...... (ii) From eq. (i) and (ii) 2d/x+y = 7/2 Hence, Amith will take to row 2d km distance downstream in 7/2 hrs = 3.5 hrs = 3 hrs 30 min.

Answer: A) 63 and 49 Explanation: Since their HCFs are 7, numbers are divisible by 7 and are of the form 7x and 7y Difference = 14 => 7x - 7y = 14=> x - y = 2 product of numbers = product of their hcf and lcm=> 7x * 7y = 441 * 7=> x * y = 63 Now, we havex * y = 63 , x - y = 2=> x = 9 , y = 7 The numbers are 7x and 7y=> 63 and 49