Question
The downstream speed of a boat is 4 km/hr more than its
upstream speed and the ratio of the speed of the boat in still water to the speed of the stream is 5:2. Find the total time taken by boat to travel 42 km downstream and 30 km upstream?Solution
Let the speed of boat in still water be x km/hr and that of stream be y km/hr. ATQ, ⇒ (x + y) – (x – y) = 4 ⇒ y = 2 km/hr ⇒ x = 2 × 5/2 = 5 km/hr Required time = [42/(5+2)] + [30/(5−2)] = 16 hr
What is the value of (a² + b²+4c²- ab-2bc-2ca) (a + b+2c):
Simplify the expression:
3x + 5y - [(7x + 3y) - (2x + y) + 4y] - xIf x, y, z are the three factors of a 3– 7a – 6, then value of x + y + z will be
Which of the following statements is correct?
I. If x = 12, y = –2 and z = –10, then x³ + y³
+ z³ = 720
II. If x + y = 48 an...
If p = 25 - q - r and pq + r(q + p) = 189, then find the value of (p² + q² + r²).
- If (x - y) = 2, then find the value of (x³ - y³ - 6xy).
If  a 2 + b 2 + c 2 = 40 & ab + bc + ca = 12 then a + b+ c = ?
If x3 + y3 = 9 and x + y=3 then the value of x4 + y4 is:
If x/y = 5/3, Find (x+y)/(x-y)?
If x = √7 + √6 and y = √7 - √6 , then the value of is (x2 + y2)/(x3 + y3).
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