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nignag [31]
3 years ago
7

Mr. Blue drove from Allston to Brockton, a distance of 105 miles. On his way back, he increased his speed by 10 mph. If the jour

ney back took him 15 minutes less time, what was his original speed?
Mathematics
2 answers:
MrMuchimi3 years ago
8 0

Answer:

60 mph

Step-by-step explanation:

andrew-mc [135]3 years ago
5 0

Answer:

His original speed was 60 mph.

Step-by-step explanation:

The average speed formula is shown below:

speed = distance / time

For the first leg of the trip Mr. Blue drove at a speed of "x" mph, for a distance of 105 miles, therefore the time that took to complete the trip is:

time 1 = distance / speed

time 1 = 105 / x h

On the second leg of the trip Mr. Blue drove faster at a speed of "x + 10" mph, so the time it took him to complete the trip was 15 minutes less, therfore:

time 2 = time1 - (15/60) = (105/x) - 0.25 = (105 - 0.25*x)/x h

Applyint the time and speed from the second leg to the average speed formula we have:

x + 10 = {105/[(105 - 0.25*x)/x]}

x + 10 = 105*x/(105 - 0.25*x)

(x + 10)*(105 - 0.25*x) = 105*x

105*x + 1050 -0.25*x² - 2.5*x = 105*x

-0.25*x² -2.5*x + 1050 = 0 /(-0.25)

x² + 10*x - 4200 = 0

x1 = [-(10) + sqrt((10)² - 4*(1)*(-4200))]/2 = 60

x2 = [-(10) - sqrt((10)² - 4*(1)*(-4200))]/2 = -70

Since his speed couldn't be negative the only possible value was 60 mph.

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Furkat [3]

Answer:

x=-1 and y=-5

Step-by-step explanation:

ሰላም!

Given expressions let them given as two equations

  • y=2+7x....... equation (1)
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Thus, substitute y=2+7x into equation (2)

- 2x + 6(2 + 7x) =  - 28 \\

simplify it

- 2x + 12 + 42x =  - 28 \\ 40x + 12 =  - 28

subtract 12 from both sides

40x + 12 - 12 =  - 28 - 12 \\ 40x =  - 40

divide both sides by 40

\frac{40x}{40}  =  \frac{ - 40}{40} \\ x =  - 1

Therefore, as we get the value of x=-1 substitute it to equation (1) and solve for variable y

y = 2 + 7x \\ y = 2 + 7( -1 ) \\ y = 2 - 7 \\ y =  - 5

To be more sure make a cross check on both of the two expressions

Thus,

1) y=2+7x .... substitute y=-5 and x=-1 and check if it is equal

-5=2+7(-1)

-5=2-5

-5=-5

2)-2x+6y=-28... substitute and check

-2(-1)+6(-5)=-28

2-30=-28... (-a)(-b)=ab

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Hope it helps!

6 0
1 year ago
Construction This section of a concrete skateboard ramp has the shape of a triangular prism. Find the volume
irina [24]

Answer:

volume = 73.3ft³

value = $194.4

Step-by-step explanation:

volume of prism = (½bh)l

=(½×4×4)×9.2

=73.6ft³

value of concrete

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73 .6ft³ : X

X : (73.6ft³ × $4.00) ÷ 1ft³

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What integer represents you getting $200 from the bank
Klio2033 [76]

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Step-by-step explanation:

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Real estate ads suggest that 56 % of homes for sale have​ garages, 27 % have swimming​ pools, and 16 % have both features. ​a) W
Marizza181 [45]

Answer:

a) 0.4

b) 0.28

c) The events are not independent

d) The events are not mutually exclusive

Step-by-step explanation:

Hi!

Lets call:

Gar = {homes with garage}

Pool = {homes with pool},  

A = {homes with pool and garage}  = Gar ∩ Pool

The data we are given is:

P(Gar) = 0.56

P(Pool) = 0.27

P(A) = 0.16

a) B = {homes with garage but not pool}. This set B is the set Gar without set A: B = Gar / A  

P(B) = P(Gar) - P(A) = 0.4

b) This is a conditional probability:

P(Pool | Gar) = P(Gar ∩ Pool) / P(Gar) = 0.16/0.56 = 0.28

c) To be independent events, it must be, by definition:

P(Gar ∩ Pool) = P(Gar) * P(Pool)

0.16 ≠ 0.56*0.27 = 0.15

Then, the events Gar and Pool are not independent

d) Gar and Pool are not mutually exclusive, because there are houses with both pool and garage. We know that because P(A) is not zero.

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HELLO PLEASE HELP!! HAVE A GOOD DAY/NIGHT!!
aliina [53]

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XP=22

6 0
3 years ago
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