Question
A motorcyclist travels the first
half of his trip at a speed of 4x km/h and the second half at a speed of 4x – 10 km/h. If his average speed for the full journey is 44 km/h, find the value of x. [x > 5]Solution
According to the question, (2 × 4x × (4x – 10)) / (4x + 4x – 10) = 44 ⇒ x(4x – 10) / (8x – 10) = 22 ⇒ 22(8x – 10) = x(4x – 10) ⇒ 176x – 220 = 4x² – 10x ⇒ 4x² – 186x + 220 = 0 ⇒ 2x(2x – 93) – 10(2x – 11) = 0 ⇒ (2x – 10)(2x – 11) = 0 ⇒ x = 11 or x = 5 ∴ x = 11
What value should come in the place of (?) in the following number series?
500, 789, 428, ?, 340, 965
Choose the missing term.
R, U, X, A, D,?
204, ?, 120, 83, 52, 23
6, 7, 16, 51, 208, ?
226, 171, 124, 85, 54, ?
4, 5, 11, 34, 137, ?
What will come in place of the question mark (?) in the following series?
4, 11, 32, 95, 284, 851, ?
8, ?, 29, 57, 113, 225
In each of the following series, one term is missing. Find the missing term.
7, 11, 19, 35, 67, ?
What should come in place of (?) question mark in the following number series.
5, 11, 23, 47, 95, ?
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