The Required ratio between the speed of the boat and speed of the water current is 8:3.
<h3>What is ratio?</h3>
In mathematics, a ratio indicates how many times one number contains another. For example, if there are eight oranges and six lemons in a bowl of fruit, then the ratio of oranges to lemons is eight to six.
Given:
Upstream time= 8 hr 48 = 8 4/5 hour
Downstream time= 4 hour
Let the man's rate upstream be x kmph and that downstream be y kmph.
Then,
distance covered upstream in 8 hrs 48 min = Distance covered downstream in 4 hrs.
x* 8 hr 48 min = y* 4 hours
x* 8 4/5= 4y
y= 11/5 x
Now,
Required ratio
(y+x)/2:(y-x)/2
= (16x/5 * 1/2): ( 6x/5 *1/2)
=8/5:3/5
=8:3
Hence, the required ratio is 8:3.
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Answer:
The value of the test statistic is -2.64.
Step-by-step explanation:
The test statistic is:

In which X is the sample mean,
is the expected(claimed) mean,
is the standard deviation and n is the size of the sample.
An automobile manufacturer claims that its van has a 40.3 miles/gallon (MPG) rating.
This means that 
After testing 250 vans, they found a mean MPG of 39.9. Assume the standard deviation is known to be 2.4.
This means, respectively, that:

So



The value of the test statistic is -2.64.
Let y = the distance between the top left corner and the bottom right corner
y^2 = 24^2 + 15^2
y^2 = 801
y = 3 * sqrt(89)
Now we can find x.
12^2 + x^2 = (3 * sqrt(89))^2
x^2 = 657
x = 3 * sqrt(73) or 25.63
It would like this for solving n