Question 428185: 1. If s is directly proportional to t, and s = 40 when t = 15, find t when s =
64.
t = 0.025 t = 24
t = 170.67 t = 40
2. If a varies directly as b, and a = 75 when b = 40, find a when b = 12.
a = 6.4 a = 0.4
a = 22.5 a = 2.25
3. If y is directly proportional to the square root of x, and y = 25 when x = 3,
find x when y = 100.
x = 3Ö 3 x = 48
x = 100 x = 12
4. If w varies directly as 2x - 1, and w = 9 when x = 2, find x when w = 15.
x = 2 x = 36
x = 5 x = 3
5. If a, b, and c are positive, and a divided by b is equal to b divided by c,
then b is called the mean proportion, or geometric mean, between a and c. Find
the mean proportion between the pair of numbers: 3 and 27.
b = 9 b = 81
b = 27 b = 18
6. If a, b, and c are positive, and a divided by b is equal to b divided by c,
then b is called the mean proportion, or geometric mean, between a and c. Find
the mean proportion between the pair of numbers: 5 and 15.
5Ö 3 b = 3
b = 75 3Ö 5
7. The acceleration of an object varies directly as the force acting on it. If a
force of 240 newtons causes an acceleration of 150 m/s², what force will cause
an acceleration of 100 m/s2?
160 newtons 16 newtons
62.5 newtons 62 newtons
8. At the grocery mart, a 575g can of green beans cost $0.39. How much will an
810 g can of green beans cost?
$0.52 $0.50
$0.55 $0.53
9. A public opinion poll found that out of a sample of 450 voters, 252 favored a
school bond issue. If 20,000 people voted, how many are likely to vote for the
bond measure?
15,714 11,200
1,120 10,100
10. The speed of an object falling from rest in a vacuum is directly
proportional to the time it has fallen. After an object has fallen for 1.5
seconds, its speed is 14.7 m/s. What is the speed after it has fallen 5 seconds?
20 m/s 51 m/s
49 m/s 50 m/s
11. Newton's law of cooling states that the rate at which an object cools varies
directly as the difference between its temperature and the temperature of the
surrounding air. At the moment a steel plate at 270 degrees Celsius is placed in
air that is at 20 degrees Celsius, its rate of cooling is 50 degrees Celsius per
minute. How fast is it cooling when the plate temperature is 100 degrees
Celsius?
24 degrees C/min 16 degrees C/min
14 degrees C/min 20 degrees C/min
Answer by richard1234(7193)   (Show Source):
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