Question
A boat takes 5 hours longer to travel 15 km upstream
than it does to travel 20 km downstream. The speed of the boat in still water is 5 km/hr. Calculate the speed of the current.Solution
Let the speed of the current be x km/hr According to the question, 15/(5 – x) – 20/(5 + x) = 5 Or, x2 + 7x – 30 = 0 Or, x2 + 10x – 3x – 30 = 0 Or, x(x + 10) – 3(x + 10) = 0 Or, (x – 3) = 0 or, (x + 10) = 0 X = -10 km/hr not possible Therefore, x = 3 km/hr Hence, option b.
What will come in place of the question mark (?) in the following series?
24, 25, 34, 59, 108, 189, ?
- What will come in place of the question mark (?) in the following series?
24, 35, 57, 90, 134, ? Choose the missing term?
B, D, F, I, L, P, ?
129, 224, 355, 528, ?, 1024
86, 127, ?, 209, 250, 291
18 29 16 31 ? 33
- What will come in place of the question mark (?) in the following series?
29, 32, 41, 68, ?, 392 81, 41, 42, 64.5, ?, 330
48, 24.5, ?, 39.75, 81.5, 206.25, 621.75
114, 146, 210, 306, 434, ?