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s2008m [1.1K]
3 years ago
9

Bill drove to town hall and back. The trip there took 1.5 hours and 2hrs on trip back. If bill's speed there was 12 mph faster t

han on the way back , find his average speed on the way back.
Mathematics
2 answers:
kogti [31]3 years ago
4 0

Answer:

 36 mph

Step-by-step explanation:

Let s represent the speed on the way back. Time is inversely proportional to speed, so the speed ratios are ...

  (speed going)/(speed coming) = (s+12)/s = 2/1.5 = (time coming back)/(time going there)

  1 +(12/s) = 4/3 . . . . . divide, simplify the ratio

  12/s = 1/3 . . . . . . .  subtract 1

  s = 36 . . . . . . . . .  multiply by 3s

Bill's average speed on the way back was 36 mph.

_____

I sometimes like to think of these problems in terms of "ratio units." We have the speed ratio:

  (s+12)/s = 2/1.5 = 4/3

The difference between s+12 and s is 12 mph, and that corresponds to the difference 4-3 = 1 ratio unit. So 3 ratio units will be 36 mph, corresponding to the value of s. Bill's speed on the way back was 36 mph.

  (48 mph)/(36 mph) = 4/3 . . . . <em>check</em>

kipiarov [429]3 years ago
3 0

Answer:

36 mph.

Step-by-step explanation:

Let x be the distance to the town hall.

Trip there:

speed (s) = distance / time

s = x / 1.5 so x = 1-5s

Trip back:

s - 12 = x / 2 so x = 2s - 24

AS they are both = to x:

1.5s = 2s - 24

0.5s = 24

s = 48.

Average speed on the way back = 48-12 = 36 mph.

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-3(2y+4) is greater that equal to 12-4y<br>​
ipn [44]

Answer:

y is less than or equal to -12

y<=-12

Step-by-step explanation:

5 0
3 years ago
Read 2 more answers
When a scientist conducted a genetics experiments with peas, one sample of offspring consisted of 943 peas, with 717 of them hav
pshichka [43]

Using the normal approximation to the binomial distribution, it is found that:

a) 0.242 = 24.2% probability of getting 717 or more peas with red flowers.

b) Since Z < 2, 717 peas with red flowers is not significantly high.

c) Since 717 peas with red flowers is not a significantly high result, we cannot conclude that the scientist's assumption is wrong.

For each pea, there are only two possible outcomes. Either they have a red flower, or they do not. The probability of a pea having a red flower is independent of any other pea, which means that the binomial distribution is used to solve this question.

Binomial distribution:

Probability of x successes on n trials, with p probability.

Normal distribution:

In a normal distribution with mean \mu and standard deviation \sigma, the z-score of a measure X is given by:

Z = \frac{X - \mu}{\sigma}

  • It measures how many standard deviations the measure is from the mean.  
  • After finding the z-score, we look at the z-score table and find the p-value associated with this z-score, which is the percentile of X.
  • If Z > 2, the result is considered <u>significantly high</u>.

If np \geq 10 and n(1-p) \geq 10, the binomial distribution can be approximated to the normal with:

\mu = np

\sigma = \sqrt{np(1-p)}

In this problem:

  • 943 peas, thus, n = 943
  • 3/4 probability of being red, thus p = \frac{3}{4} = 0.75.

Applying the approximation:

\mu = np = 943(0.75) = 707.25

\sigma = \sqrt{np(1-p)} = \sqrt{943(0.75)(0.25)} = 13.297

Item a:

Using continuity correction, this probability is P(X \geq 717 - 0.5) = P(X \geq 716.5), which is <u>1 subtracted by the p-value of Z when X = 716.5</u>.

Then:

Z = \frac{X - \mu}{\sigma}

Z = \frac{716.5 - 707.25}{13.297}

Z = 0.7

Z = 0.7 has a p-value of 0.758.

1 - 0.758 = 0.242

0.242 = 24.2% probability of getting 717 or more peas with red flowers.

Item b:

Since Z < 2, 717 peas with red flowers is not significantly high.

Item c:

Since 717 peas with red flowers is not a significantly high result, we cannot conclude that the scientist's assumption is wrong.

A similar problem is given at brainly.com/question/25212369

6 0
3 years ago
Indicate the equation of the line that is the perpendicular bisector of the segment with endpoints (4, 1) and (2, -5).
vladimir2022 [97]
What we know:
line P endpoints (4,1) and (2,-5) (made up a line name for the this line)
perpendicular lines' slope are opposite in sign and reciprocals of each other
slope=m=(y2-y1)/(x2-x1)
slope intercept for is y=mx+b

What we need to find: 
line Q (made this name up for this line) , a perpendicular bisector of the line p with given endpoints of  (4,1) and (2,-5)

find slope of line P using (4,1) and (2,-5) 
m=(-5-1)/(2-4)=-6/-2=3

Line P has a slope of 3 that means Line Q has a slope of -1/3.

Now, since we are looking for a perpendicular bisector, I need to find the midpoint of line P to use to create line Q. I will use the midpoint formula using line P's endpoints (4,1) and (2,-5).

midpoint formula: [(x1+x2)/2, (y1+y2)/2)]
midpoint=[(4+2)/2, (1+-5)/2]
              =[6/2, -4/2]
              =(3, -2)

y=mx=b       when m=-1/3 slope of line Q and using point (3,-2) the midpoint                                 of line P where line Q will be a perpendicular bisector

(-2)=-1/3(3)+b               substitution
-2=-1+b                           simplified
-2+1=-1+1+b                 additive inverse
-1=b

Finally, we will use m=-1/3 slope of line Q and y-intercept=b=-1 of line Q
y=-1/3x-1



4 0
3 years ago
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Jesse Stroh the coin in her bank she made 7 stacks of 6 diamonds and 8 stacks of 5 nickels she then found one diamond and 1 nick
fiasKO [112]
So there are 8 stacks of 5 nickels which means that the equation would be simply 8 * 5 which equals 40 nickels. Then, 7 stacks of 6 dies would equal 42. Then she found one more dime and one more nickel which means she has 41 nickels and 43 dimes. In all, she has 84 dimes and nickels. 
7 0
3 years ago
Can some please help
enyata [817]

Answer:

a

Step-by-step explanation:

6(8x +5y=-7)= 48x +30y= -42

-5(-7x+6y=-4)= 35x -30y= 20

The ys would cancel out

4 0
3 years ago
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