Question
A boat takes 20 hours to go 200 km upstream. If the boat
doubles its speed, it can cover 200 km downstream in 4 hours. Find the speed of the stream.Solution
Upstream speed of the boat = 200 ÷ 20 = 10 km/h Let speed of the boat in still water = 'x' km/h and speed of the stream = 'y' km/h. So, x - y = 10 ...... (I) Downstream speed when doubled = 200 ÷ 4 = 50 So, 2x + y = 50 ......... (II) Adding (I) and (II): 3x = 60 x = 20 Then, 20 - y = 10 y = 10 Speed of the stream = 10 km/h
5 + 2 × 3 ÷ (3 × 2) ÷ 4
What will come in the place of question mark (?) in the given expression?
{122 + (66/4) + (252/8)} ÷ 8 = (?)1/2
(152 × 24 + 2540)/25 = 44464 ÷ ?
(72 + 30) ÷ 6 + [{75 ÷ 25) + 6} × 2] = ?
12.5% of (100 + ?) = 40
(11/12) × (18/22) × (4/3) + 3 = ?2
- What will come in the place of question mark (?) in the given expression?
435 + 729 - 282 x 2 = ? + 225 + 125 What will come in the place of question mark (?) in the given expression?
{(16 × 25) ÷ 32} × 12 = ? – 200
240 + 25% of 420 – 145 =? + (2.5 + 8.5) 2
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