A swimming pool already contains

Mathematics

1 answer:

xenn [34]2 years ago

6 0

Answer:

Rate of change = 3 gallons/minute

Starting volume = 30 gallons

Step-by-step explanation:

A graph of the pool's water level would be useful. The slope of the line would represent the rate of change for filling the pool. It will also help us determine the amount of water that was in the pool to start. Although it is tempting to say the rate of fill is 45gallons/5 minutes, or 9 gallons/minute, it is not correct. The pool already started with an unknown volume of water. The rate of change after 5 minutes, however, can be used. The problem states it is being added at a constant rate. Let's find an equation for a line, in the format of y=mx+b, where m is the slope (rate of change) and b is the y-intercept.

We'll let y represent the volume of water in the pool, and x will be the time in minutes. The y-intercept will give us the amount of water in the pool at the start (x = 0).

The slope can be determined between the two given points:

(5,45) and (30,120):

Slope = Rise/Run [The change in y divided by the change in x].

Rise = (120 - 45) = 75

Run = (30-5) = 25

Slope = 75/25 or 3

The line, so far, becomes y=3x + b

The slope of 3 has units of gallons/minute. It is the rate at which the pool is being filled.

We can find b, the starting volume of water, by using one of the two points in the equation and solving for b:

y=3x + b [I'll use (5,45)]

45 = 3*(5) + b

b = 30 gallons

The pool had 30 gallons to start (at x = 0(minutes))

See the graph of the line, attached.

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Suppose that 80 percent of all statisticians are shy, whereas only 15 percent of all economists are shy. Suppose also that 90 pe

Anna71 [15]

Answer:

37.21% probability that the person is a statistician.

Step-by-step explanation:

We have these following probabilities:

An 80% probability that a statistican is shy.

A 15% probability that an economist is shy.

At the gathering, a 90% probability that a person is an economist.

At the gathering, a 10% probability that a person is a statistican.

If you meet a shy person at random at the gathering. What is the probability that the person is a statistician?

This can be formulated as the following question:

What is the probability of B happening, knowing that A has happened.

It can be calculated by the following formula

$P = \frac{P(B).P(A/B)}{P(A)}$

Where P(B) is the probability of B happening, P(A/B) is the probability of A happening knowing that B happened and P(A) is the probability of A happening.

What is the probability that the person is a statistican, given that he is shy?

P(B) is the probability of the person being a statistican. So P(B) = 0.1.

P(A/B) is the probability of a statistican being shy, so P(A/B) = 0.8.

P(A) is the probability of a person being a shy. This is 15% of 90%(economists) and 80% of 10%(statisticans). So

$P(A) = 0.15*0.9 + 0.8*0.1 = 0.215$