Answer: Downhill:10mph Uphill:5mph
Step-by-step explanation:
We are looking for Dennis’s downhill speed.
Let
r=
Dennis’s downhill speed.
His uphill speed is
5
miles per hour slower.
Let
r−5=
Dennis’s uphill speed.
Enter the rates into the chart. The distance is the same in both directions,
20
miles.
Since
D=rt
, we solve for
t
and get
t=
D
r
.
We divide the distance by the rate in each row and place the expression in the time column.
Rate
×
Time
=
Distance
Downhill
r
20
r
20
Uphill
r−5
20
r−5
20
Write a word sentence about the time.
The total time traveled was
6
hours.
Translate the sentence to get the equation.
20
r
+
20
r−5
=6
Solve.
20(r−5)+20(r)
40r−100
0
0
0
=
=
=
=
=
6(r)(r−5)
6
r
2
−30r
6
r
2
−70r+100
2(3
r
2
−35r+50)
2(3r−5)(r−10)
Use the Zero Product Property.
(r−10)=0
r=10
(3r−5)=0
r=
5
3
The solution
5
3
is unreasonable because
5
3
−5=−
10
3
and his uphill speed cannot be negative. So, Dennis's downhill speed is
10
mph and his uphill speed is
10−5=5
mph.
Check. Is
10
mph a reasonable speed for biking downhill? Yes.
Downhill:
10 mph
5 mph⋅
20 miles
5 mph
=20 miles
Uphill:
10−5=5 mph
(10−5) mph⋅
20 miles
10−5 mph
=20 miles
The total time traveled was
6
hours.
Dennis’ downhill speed was
10
mph and his uphill speed was
5
mph.
Answer:
C
Step-by-step explanation:
The perimeter of a figure is found by adding the sides of all the figures. The figure has sides 13 and 9. Its height is 4 so each of those sides is about 4 feet. So the perimeter is 13+9+4+4 = 30
C is the best solution.
Answer:
As number of gallons of gas minus 9 leaves 3 gallons, denote g as number of gallons: g - 9 >=3.
Then g>= 12
The slope of a line is constant because the acceleration is equal to zero.
The slope of a line is always just (y2-y1)/(x2-x1), so in this case:
m=(-7-6)/(4--6)
m=-13/10
m=-1.3
Answer: The answer is 0.38
Step-by-step explanation:
Well, everything is given, as stated in the question "the probability that a student is a girl and in an art class is 0.20."
It's given that the probability that a student is a girl is 0.52.
However, in the question, it said that it's given a student is a girl.
You have the probability that a student is a girl and in art class, so you need to find what 0.52 was multiplied by which would be the probability of someone being in art class. Knowing this you can do 0.20 / 0.52 to get 0.38.
