Answer: the rate of the jet in still air is 685 mph and the rate of the jetstream is 75 mph
Step-by-step explanation:
Let x represent the rate of the jet in still air.
Let y represent the rate of the jet jetstream.
Distance = speed × time
Flying against the jetstream, a jet travels 3050 miles in 5 hours. This means that the total speed of the jet would be (x - y) mph. Therefore,
3050 = 5(x - y)
3050/5 = x - y
x - y = 610 - - - - - - - - - - - - - -1
Flying with the jetstream, the same jet travels 3800 miles in 4 hours. This means that the total speed of the jet would be (x + y) mph. Therefore,
3800 = 4(x + y)
3800/5 = x + y
x + y = 760 - - - - - - - - - - - - - -2
Adding equation 1 to equation 2, it becomes
2x = 1370
x = 1370/2 = 685mph
Substituting x = 685 into equation 1, it becomes
685 - y = 610
y = 685 - 610 = 75mph
Answer:
8 hours
Step-by-step explanation:
Given:
Sheyna drives to the lake with average speed of 60 mph and

Sheyna drives back from the lake with average speed of 36 mph

It took 2 hours less time to get there than it did to get back.
Let
be the time taken to drive to lake.
Let
be the time taken to drive back from lake.
hrs ..... (1)
To find:
Total time taken = ?

Solution:
Let D be the distance to lake.
Formula for time is given as:


Putting in equation (1):

So,

So, the answer is:

Another way to solve this is to use the Midpoint Formula. The midpoint of a segment joining points

and

is

So the midpoint of your segment is

Perhaps it helps to see that the x-coordinate of the midpoint is just the average of the x-coordinates of the points. Ditto for the y-coordinate of the midpoint; just average the y's.
Answer:
The sample space for selecting the group to test contains <u>2,300</u> elementary events.
Step-by-step explanation:
There are a total of <em>N</em> = 25 aluminum castings.
Of these 25 aluminum castings, <em>n</em>₁ = 4 castings are defective (D) and <em>n</em>₂ = 21 are good (G).
It is provided that a quality control inspector randomly selects three of the twenty-five castings without replacement to test.
In mathematics, the procedure to select k items from n distinct items, without replacement, is known as combinations.
The formula to compute the combinations of k items from n is given by the formula:

Compute the number of samples that are possible as follows:


The sample space for selecting the group to test contains <u>2,300</u> elementary events.
Answer:
B.
Step-by-step explanation:
The opposite of 5/2 is -5/2 which is -2 1/2 and the opposite of -1/2 is 1/2.