A boat travels 42 km against the current and 72 km with the current in a total time of 8 hours. Additionally, it covers a distance of 56 km in still water in 4 hours. Given that the speed of the current exceeds 1.75 km/h, by what percentage is the boat's speed upstream lower than its speed downstream?
Speed of the boat in still water = 56/4 = 14 km/h Let the speed of the stream = x km/h So according to question: 42/(14 – x) + 72/(14 + x) = 8 294 + 21x + 504 –36x = 784 – 4x2 4x2 – 15x + 14 = 0 4x2 – 8x – 7x + 14 = 0 4x(x – 2) – 7(x – 2) = 0 (4x – 7)(x – 2) = 0 x = 2, 7/4 = 2, 1.75 As the speed of the stream is greater than 1.75, the value of x = 2 So the downstream speed and upstream speed of the boat are 16 km/h and 12 km/h respectively. So the desired percentage = (16 – 12)/16 × 100 = 25%
100 gram of ice at 0°C is mixed with 100 gram of water at 80°C. What will be the final temperature of the mixture ?
What is the viscosity of an ideal fluid?
In the periodic table of elements, what happens to the atomic radius as you move from left to right across a period?
If water smells bad, then that odor can be removed by adding:
What is the common characteristic of elements in the same group of the periodic table?
Which of the following relation is correct?
In which form is iron ore primarily found in nature?
Magnesium oxide (MgO) + Water (H2O) = ?
Compressed natural gas (CNG) primarily consists of which gas?
Which chemical is used to generate light to weld metals?
