Let x be rate of boat in still water
let y be rate of current
we use this equation to relate quantities:
distance = speed · time
we have two unknowns so we might need to create a system of equationss
upstream:
speed (in km/h) = x - y
(we get speed of boat then subtract the current's speed from it since current is going against boat direction)
time = 3 hours
distance = 144 km
downstream:
speed (in hm/h) = x + y
(we get speed of boat then add the current's spd from it since current is going against boat direction)
time = 2 hours
distance = 144 km (same distance upstream and downstream)
using distance = speed times time
for upstream
144 = 3(x-y)
144 = 3x - 3y
for downstream
144 = 2(x+y)
72 = x + y
system of eqns:
144 = 3x - 3y
72 = x + y
solve by substitution: move 72 = x + y into x = 72 - y and subst into other equation for x
144 = 3(72 - y) - 3y
144 = 216 - 3y - 3y
144 = 216 - 6y
144 - 216 = -6y
-72 = -6y
y = 12 km/h
Use x = 72 - y to find x with y = 12: x = 72 - 12 = 60 km/h
rate of boat in still water is 60 km/h
rate of the current is 12 km/h
Mean: ( 9 + 7 + 6.5 + 7.5 + 7 + 8 + 5 + 6 + 7.5 + 8 ) : 10 = 7.15
Variance:
(Sigma)² = ( 1.85² + 0.15² + 0.65² + 0.35² + 0.15² + 0.85² + 2.15² + 1.15² + 0.35² + 0.85² ) : 10 ≈ 1.15
Answer: C ) 1.15
Answer:
There is a 38.97% probability that this student earned an A on the midterm.
Step-by-step explanation:
The first step is that we have to find the percentage of students who got an A on the final exam.
Suppose 13% students earned an A on the midterm. Of those students who earned an A on the midterm, 47% received an A on the final, and 11% of the students who earned lower than an A on the midterm received an A on the final.
This means that
Of the 13% of students who earned an A on the midterm, 47% received an A on the final. Also, of the 87% who did not earn an A on the midterm, 11% received an A on the final.
So, the percentage of students who got an A on the final exam is

To find the probability that this student earned an A on the final test also earned on the midterm, we divide the percentage of students who got an A on both tests by the percentage of students who got an A on the final test.
The percentage of students who got an A on both tests is:

The probability that the student also earned an A on the midterm is

There is a 38.97% probability that this student earned an A on the midterm.
(a) The equation of the tangent line can be written as
.. 3(x +6) -4(y -8) = 0
.. 3x -4y = -50
.. y = (3/4)x +25/2 . . . the equation of the tangent line
(b) The point of tangency will be the intersection of the circle with the perpendicular line through the circle center, y = (-1/5)x. A graphing calculator shows that point to be
.. (9.81, -1.96)
This is<span> not the exact, precise </span>definition<span> of a </span>limit. If you would like to see the more precise and mathematical definition<span> of a </span>limit<span> you should check out the The </span>Definition<span> of a </span>Limit<span> section at the end of this chapter. The </span>definition<span> given above </span>is<span> more of a “working” </span>definition<span>.</span>