Answer: D) 1000(p - q) + qr Explanation: We need to find the total cost to send r messsages, r > 1000. The first 1000 messsages will cost Rs.p each (Or)  The total cost of first 1000 messsages = Rs.1000p The remaining (r - 1000) messsages will cost Rs.q each (Or) The cost of the (r - 1000) = Rs.(r - 1000)y   Therefore, total cost = 1000p + rq - 1000q = 1000(p - q) + qr

Answer: C) 8 and 1 kmph Explanation: Downstream speed = 72km/8hrs  = 9 kmphupstream speed = 84km/12hrs = 7 kmphspeed of boat = avg of downstream and upstream speedsspeed of boat = (9+7)/2kmph = 8 kmph.current speed = half of the difference of downstream and upstream speedscurrend speed = (9-7)/2kmph = 1 kmph

Answer: C) 31.4208 and 62.8416 Explanation: Birds speeds in mtrs/sec is 'x' and '2x' .While flying from Engine to end, relative speed = (x+10) m/secfrom end to engine, flying speed = (2x - 10) mtr/secso 1000/(x+10) + 1000/(2x-10) = 187.5 secssolving it, we getso x = 8.728 m/sec and 2x= 17.456 m/sec x = 31.4208 km/hr and 2x = 62.8416 km/hr.

Answer: B) 80 kgs Explanation: Say total cost price of tea is x.Then total profit at a rate of 15% is = (15x/100)According to question,15x/100 = 60so x = 400C.p of the tea is Rs. 400.so total selling price will be = (400+60) = Rs.460so the quantity of the tea will be = (460/5.75) = 80kg.

Answer: C) 9 & 21 Explanation: Let the two numbers be x and y Given x : y = 3 : 7 .....(1) Now, x+6 : y+6 = 5 : 9 .....(2) From (1), x = 3y/7 From (2), 5y - 9x = 24 => 5y - 9(3y/7) = 24 => y = 21 => From(1), x = 9 Hence, the two numbers be 9 and 21

Answer: D) 12 p.m. Explanation: Assume both trains meet after 'p' hours after 7 a.m.Distance covered by train starting from A in 'p' hours = 20p kmDistance covered by train starting from B in (p-1) hours = 25(p-1)Total distance = 200=> 20x + 25(x-1) = 200=> 45x = 225=> p= 5Means, they meet after 5 hours after 7 am, ie, they meet at 12 p.m.

Answer: C) 3/4 Explanation: Let A, B, C be the respective events of solving the problem and A , B, C be the respective events of not solving the problem. Then A, B, C are independent event ∴A, B, C are independent events Now,  P(A) = 1/2 , P(B) = 1/3 and P(C)=1/4  PA=12, PB=23, PC= 34 ∴ P( none  solves the problem) = P(not A) and (not B) and (not C)                     = PA∩B∩C                    = PAPBPC         ∵ A, B, C are Independent                                          =  12×23×34                     = 14   Hence, P(the problem will be solved) = 1 - P(none solves the problem)                  = 1-14= 3/4

Answer: C) 81 Explanation: The series follows the following pattern.   4   16 = 42   37 = 12+62   58 = 32+72   81 ≠52+82.   Here every number is based on the digits of previous number. Hence, 81 is the wrong number in the given series.