A boat takes a total time of twelve hours to travel 105 kms upstream and the same distance downstream. The speed of the boat in still water is six times of the speed of the current. What is the speed of the boat in still water? (In km/hr)
Answer: Option C. Let ‘x’ be the speed of Boat in still water, and ‘y’ be the speed of current. Then, according to the question, Speed of the boat in still water = 6 speed of current x = 6y Also given that , 105/(x+y) +105/(x-y) =12 105/7y +105/5y =12 12y=36 y=3 Therefore, x= 6×3=18 Speed of the boat in still water= 18kmph
At 60% of its usual speed, a train of length L meters crosses platform 240 meters long in 15 seconds. At its usual speed, the train crosses a pole in 6 seconds. What is the value of L (in meters)?
Answer: Option D. Let usual speed = S m/s. According to the question, 60% of S= (L+240)/15 9S= L+240………… (i) Also given that, S = L/6 L = 6S …. (ii) From (i) & (ii) 9S= 6S+240 3S= 240 S=80 m/s From (ii) L= 6×80 =480 m
P, Q and R have a certain amount of money with themselves. Q has 50% more than what P has, and R has 1/3rd of
Answer: Option D. Assume that P has 2x amount. Therefore, Q = 3x amount (50% more than P) And R = 3x × 1/3 = x Ratio of P : Q : R = 2x : 3x : x = 2 : 3 : 1 Thus, P alone have = (2/6) × 240 = Rs. 80
Suri gave 25% of her monthly salary to her mother. From the remaining salary, she paid 15% towards rent and 25%, she kept aside for her monthly expenses. The remaining amount she kept in bank account. The sum of the amount she kept in bank and that she gave to her mother was Rs. 42000. What was her monthly salary?
Answer: Option B. Let x be the total income (75/100*60/100)x + 25/100x = 42000 Solving, x = 60000
At present, Ami’s age is twice Dio’s age and Cami is two years older than Ami. Two years ago, the respective ratio between Dio’s age at that time and Cami’s age at that time was 4: 9. What will be Ami’s age four years hence?
Answer: Option A D; A = 2D; C = A+2 = 2D+2 Given, D-2/(2D+2)-2 = 4/9 Solving, D = 18 Years and A = 36+4 = 40 years.