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DerKrebs [107]
3 years ago
9

A car traveled from city a to city b at an average speed of 3x miles per hour, where x > 0. the car then immediately returned

along the same route at an average speed of 4x miles per hour. in terms of x, what was the car's average speed, in miles per hour, for the round trip
Mathematics
1 answer:
dlinn [17]3 years ago
8 0
This is a classic question on Speed, time, & distance.

1. When time traveled in each segment is constant, then average speed is simple mean of speeds.

2. When distance traveled in each segment is constant, then average speed is reciprocal of simple mean of reciprocal of speeds. It is basically called Harmonic mean.

So this question falls in the category of 2.

=> So, average speed = Reciprocal of mean of reciprocals of 40 & 50.

=> Average speed = Reciprocal of mean of 1/40 & 1/50.

<span>=> Average speed = Reciprocal of (1/40 + 1/50)/2 = Reciprocal of (5+4)/400 = 44 4/9 .
Hope this helps</span>
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Complete question is:

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Answer:

probability that these 4 will contain at least two more high-risk drivers than low-risk drivers = 0.0488

Step-by-step explanation:

Let H represent High risk

M represent moderate risk

L represent Low risk.

The following combinations will satisfy the condition that there are at least two more high-risk drivers than low-risk drivers: HHHH, HHHL, HHHM, HHMM

The HHHH case has probability 0.2 ⁴ = 0.0016

The HHHL case has probability 4 × 0.2³ × 0.3 = 0.0096 (This is because L can be in four different places)

Similarly, the HHHM case has probability 4 × 0.2 ³ × 0.5 = 0.016

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Summing all these probabilities, we have;

0.0016 + 0.0096 + 0.016 + 0.0216 = 0.0488

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2 years ago
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