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Bond [772]
3 years ago
11

if it would take billy an hour to race over to his girlfriends house and two hours if he went 20 miles per hour slower how far a

ways does billys girlfriend live
Mathematics
1 answer:
mel-nik [20]3 years ago
5 0
Recall your d = rt, distance = rate * time.

now, let's say she lives "d" miles away, and so if Billy goes say at "r" mph fast to her house, he gets there in 1hr.

now, if he goes 20 mph slower, namely " r - 20 " mph, he gets there in 2 hours, same "d" miles.

\bf \begin{array}{lccclll}
&\stackrel{miles}{distance}&\stackrel{mph}{rate}&\stackrel{hours}{time}\\
&------&------&------\\
\textit{Billy}&d&r&1\\
\textit{slower Billy}&d&r-20&2
\end{array}
\\\\\\
\begin{cases}
d=r(1)\implies d=\boxed{r}\\
d=2(r-20)\\
----------\\
d=2\left( \boxed{d}-20 \right)
\end{cases}
\\\\\\
d=2d-40\implies 40=d
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We need 2880 person-hours and we have 12 people.

When we divide the work between them: 2880/12 = 240 hours required to complete.
6 0
3 years ago
You play the following game against your friend. You have 2 urns and 4 balls One of the balls is black and the other 3 are white
Rom4ik [11]

Answer:

Part a: <em>The case in such a way that the chances are minimized so the case is where all the four balls are in 1 of the urns the probability of her winning is least as 0.125.</em>

Part b: <em>The case in such a way that the chances are maximized so the case  where the black ball is in one of the urns and the remaining 3 white balls in the second urn than, the probability of her winning is maximum as 0.5.</em>

Part c: <em>The minimum and maximum probabilities of winning  for n number of balls are  such that </em>

  • <em>when all the n balls are placed in one of the urns the probability of the winning will be least as 1/2n</em>
  • <em>when the black ball is placed in one of the urns and the n-1 white balls are placed in the second urn the probability is maximum, as 0.5</em>

Step-by-step explanation:

Let us suppose there are two urns A and A'. The event of selecting a urn is given as A thus the probability of this is given as

P(A)=P(A')=0.5

Now the probability of finding the black ball is given as

P(B)=P(B∩A)+P(P(B∩A')

P(B)=(P(B|A)P(A))+(P(B|A')P(A'))

Now there can be four cases as follows

Case 1: When all the four balls are in urn A and no ball is in urn A'

so

P(B|A)=0.25 and P(B|A')=0 So the probability of black ball is given as

P(B)=(0.25*0.5)+(0*0.5)

P(B)=0.125;

Case 2: When the black ball is in urn A and 3 white balls are in urn A'

so

P(B|A)=1.0 and P(B|A')=0 So the probability of black ball is given as

P(B)=(1*0.5)+(0*0.5)

P(B)=0.5;

Case 3: When there is 1 black ball  and 1 white ball in urn A and 2 white balls are in urn A'

so

P(B|A)=0.5 and P(B|A')=0 So the probability of black ball is given as

P(B)=(0.5*0.5)+(0*0.5)

P(B)=0.25;

Case 4: When there is 1 black ball  and 2 white balls in urn A and 1 white ball are in urn A'

so

P(B|A)=0.33 and P(B|A')=0 So the probability of black ball is given as

P(B)=(0.33*0.5)+(0*0.5)

P(B)=0.165;

Part a:

<em>As it says the case in such a way that the chances are minimized so the case is case 1 where all the four balls are in 1 of the urns the probability of her winning is least as 0.125.</em>

Part b:

<em>As it says the case in such a way that the chances are maximized so the case is case 2 where the black ball is in one of the urns and the remaining 3 white balls in the second urn than, the probability of her winning is maximum as 0.5.</em>

Part c:

The minimum and maximum probabilities of winning  for n number of balls are  such that

  • when all the n balls are placed in one of the urns the probability of the winning will be least given as

P(B|A)=1/n and P(B|A')=0 So the probability of black ball is given as

P(B)=(1/n*1/2)+(0*0.5)

P(B)=1/2n;

  • when the black ball is placed in one of the urns and the n-1 white balls are placed in the second urn the probability is maximum, equal to calculated above and is given as

P(B|A)=1/1 and P(B|A')=0 So the probability of black ball is given as

P(B)=(1/1*1/2)+(0*0.5)

P(B)=0.5;

5 0
3 years ago
Is 6:9 reater than less than or equal to 9:12
insens350 [35]

Answer:

less than

Step-by-step explanation:

6/9 is less than 9/12

6/9=.6666666666666666666666666

9/12=.75


.666666<.75

5 0
3 years ago
What’s the slope and y - intercept of this equation ?
zavuch27 [327]

Answer:

Slope = -\frac{7}{3}

Y-intercept = 4

Step-by-step explanation:

-> See attached

-> This equation is in slope-intercept form.

         [] When we use y = mx + b, the m is the slope and the b is our y-intercept.

Have a nice day!

     I hope this is what you are looking for, but if not - comment! I will edit and update my answer accordingly.

- Heather

5 0
3 years ago
Read 2 more answers
The graphs show information about the different journeys of 4 people.
xxTIMURxx [149]

Answer:

A) b

B) c

Step-by-step explanation:

A) a large distance is covered in a short period of time but then the speed decreases

B) the person travels some distance but then returns to their starting point for a while(their home) and then starts on their journey again

4 0
2 years ago
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