There has been a great deal of controversy over the last several years regarding what types of surveillance are appropriate to prevent terrorism. suppose a particular surveillance system has a 98% chance of correctly identifying a future terrorist and a 99.9% chance of correctly identifying someone who is not a future terrorist. if there are 1,000 future terrorists in a population of 300 million, and one of these 300 million is randomly selected, scrutinized by the system, and identified as a future terrorist, what is the probability that he/she actually is a future terrorist? (round your answer to six decimal places.)

Given that a person was identified as a future terrorist, there is a 2.8544% probability that he/she actually is a future terrorist.

Step-by-step explanation:

There are 1000 future terrorists in a population of 300,000,000. So the probability that a randomly selected person in this population is a terrorist is:

So, we have these following probabilities:

A 99.9997% probability that a randomly chosen person is not a terrorist.

A 0.0003% probability that a randomly chosen person is a terrorist.

A 98% probability that a future terrorist is correctly identified

A 99.9% chance of correctly identifying someone who is not a future terrorist. This also means that there is a 0.01% probability of someone who is not a terrorist being identified as one.

This can be formulated as the following problem:

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

It can be calculated by the following formula

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.

Here we have:

What is the probability that the person is a terrorist, given that she was identified as a terrorist.

P(B) is the probability that the person is a terrorist. So

P(A/B) is the probability that the person was identified as a terrorist, given that she is a terrorist. The problem states that the system has a 98% chance of correctly identifying a future terrorist, so

P(A) is the probability of a person being a identified as a terrorist. So

is the probability that a person is a terrorist and was identified as one. So:

is the probability that a person is not a terrorist and, but was identified as one. So:

So

The answer is:

Given that a person was identified as a future terrorist, there is a 2.8544% probability that he/she actually is a future terrorist.

"it's not the heat, it's the humidity".   that's a partly valid phrase you may have heard in the summer, but it's actually both.   the heat index, also known as the apparent temperature, is what the temperature feels like to the human body when relative humidity is combined with the air temperature.   this has important considerations for the human body's comfort.   when the body gets too hot, it begins to perspire or sweat to cool itself off.   if the perspiration is not able to evaporate, the body cannot regulate its temperature.   evaporation is a cooling process.   when perspiration is evaporated off the body, it effectively reduces the body's temperature.   when the atmospheric moisture content (i.e. relative humidity) is high, the rate of perspiration from the body decreases.   in other words, the human body feels warmer in humid conditions.   the opposite is true when the relative humidity decreases because the rate of perspiration increases.   the body actually feels cooler in arid conditions.   there is direct relationship between the air temperature and relative humidity and the heat index, meaning as the air temperature and relative humidity increase (decrease), the heat index increases (decreases).

step-by-step explanation: