Question
Motor boat covers a certain distance downstream in 5
hours. It covers the same distance upstream in 7(1/2) hour. If the speed of the water is 4.5 km/hr, then the speed of the boat in still water is:Solution
Let the distance be ‘D’ km According to the question, Downstream speed x + y = d/5 or d = 5 (x+y) .......... (i) Upstream speed x-y = (d×2)/15 or d = (15(x-y))/2 ........... (ii) Comparing (i) & (ii) 5 (x+y) = (15(x-y))/2  10(x+y) = 15(x-y) 2(x+y) = 3(x-y) 2x + 2y = 3x - 3x x = 5y Hence, y = Speed of the current = 4.5 km/hour. Speed of boat, x = 5 × 4.5 = 22.5 km/hr
If 'A' means '×', 'B' means '÷', 'C' means '+', and 'D' means '-', then what will come in the place of '?' in the given expression?
180 A 5 ...
157 + 256 – 88 ÷ 8 × 4 = 117
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16 – 8 ÷ 4 + 5 × 2 = 8 If '-' means 'division', '÷' means 'addition', '+' means 'multiplication' and ' X ' means 'subtraction', then what is the value of the following expres...
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5 + 3 × 8 – 12 ÷ 4 = 3 Himani goes 9m north and turns left and walks 6m. Again, she turns to her right and walks 5m. After this, she takes another right turn and walks 8m. So,...
If in a certain code language ‘+’ represents ‘×’, ‘–’ represents ‘+’, ‘×’ represents ‘÷’ and ‘÷’ represents ‘–’....
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 By interchanging which two signs the question will be correct?
15 + 5 ÷ 2 – 9 × 3 = 22
Read the directions carefully and answer the following questions.
If ' + ' means '-', ' × ' means '+', ' - ' means '÷', and ' ÷ ' means '×'...
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