A river is flowing at the rate of 2.4 miles an hour when a boy rows across it. If the boy rows at a still-water speed of 3.1 mil
es per hour and heads the boat perpendicular to the direction of the current. The ground speed of the boat is _____ miles per hour.
1 answer:
Answer:
3.9 mi/h
Step-by-step explanation:
If the boy is rowing perpendicular to the current, the two vectors form a right triangle.
AB represents the downstream current, BC is the speed across the river, and AC is the ground speed of the boat
AC^2 = 2.4^2 + 3.1^2 =5.76 + 9.61 = 15.37
AC = sqrt(15.37) = 3.9 mi/h
The boat's speed over the ground is 3.9 mi/h.
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Answer:
<h2>84, 42</h2>Step-by-step explanation:
Answer:
Sunayana's income is ₹25000 and expenditures are ₹15000.
Step-by-step explanation:
Let i denote the monthly income and e denote the expenditures.
We know that the ratio of the monthly income to expenditure is 5:3. So, we can write the following proportion:
Let's multiply both sides by e. This yields:
We know that when the income is <em>increased</em> by 5000 and the expenditures are <em>decreased </em>by 3000, the new ratio is 5:2. So, we can write the following proportion:
Let's multiply both sides by :
Since we know that , substitute:
So, let's solve for the expenditures. Distribute the right:
Subtract from both sides:
Subtract 5000 from both sides:
Multiply both sides by -6/5. So, the expenditures are:
We can use the original ratio to find Sunayana's income:
Substitute 15000 for e. Evaluate:
So, Sunayana's income is ₹25000 and expenditures are ₹15000.
And we're done!
Edit: Wrong currency, sorry about that!