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lord [1]
3 years ago
5

A car travelled 100 km with half the distance at 40 km/h and the other half at 80 km/h. Find the average speed of the car for th

e whole journey.
Mathematics
1 answer:
Nana76 [90]3 years ago
6 0
We must look at this question in steps
The first half of the journey is travelled at 40 km/h
Half of 100km is 50 km
Using the formula
Distance = Speed x Time
Speed = Distance / Time
Time = Distance / Speed
We can work out the time:

50km / 40km/h = 1.25 hours

Next we look at the second half of the journey
50km at 80km/h
50km / 80km/h = 0.625 hours

Add together both times to work out how long the entire journey took
1.25 + 0.625 = 1.875 hours

Using the Speed formula from before
Speed = 100km / 1.875 =
53 1/3 km/h or 53.3 recurring km/h
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The best and most correct answer among the choices provided by the first question is letter E which is all of the above.


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7 0
3 years ago
Write the equation of the line that passes through (-1, 3) and is parallel to the line y = -x + 1.
ra1l [238]

Answer:

Step-by-step explanation:

y = -x + 1......same as y = -1x + 1.....in y = mx + b form, ur slope is in the m position....so the slope of this line is -1.

a parallel line will have the same slope.

(-1,3)...x = -1 and y = 3

slope(m) = -1

y = mx + b.....we have x,y, and m....now we need to find y int (b)

3 = -1(-1) + b

3 = 1 + b

3 - 1 = b

2 = b

so ur parallel equation is : y = -1x + 2...or just y = -x + 2

7 0
2 years ago
A professor's son, having made the wise decision to drop out of college, has been finding his way in life taking one job or anot
Trava [24]

Answer:

88.88% probability that it endures for less than a year and a half

Step-by-step explanation:

Problems of normally distributed samples can be solved using the z-score formula.

In a set with mean \mu and standard deviation \sigma, the zscore of a measure X is given by:

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

The Z-score 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. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

In this question, we have that:

\mu = 66, \sigma = 10

The next career begins on Monday; what is the likelihood that it endures for less than a year and a half?

One year has 52.14 weeks. So a year and a half has 1.5*52.14 = 78.21 weeks.

So this probability is the pvalue of Z when X = 78.21.

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

Z = \frac{78.21 - 66}{10}

Z = 1.22

Z = 1.22 has a pvalue of 0.8888

88.88% probability that it endures for less than a year and a half

6 0
3 years ago
Help with my math i will mark brainliest
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The answer is $15 more per T-shirt
4 0
2 years ago
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A straight line passes through points (−2, 24) and (6, −8).
Triss [41]

Answer:

b.

Step-by-step explanation:I think so

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