Question Details

Let X is a continuous random variable denoting the temperature measured. The range of temperature is [0, 100] degree Celsius and let the probability density function of X be f(x) = 0.01 for 0 ≤ X ≤ 100. The mean of X is __________.

Options

A

2.5

B

5.0

C

25.0

D

50.0

Correct Answer :

50.0

Solution :

The correct option is 50.0.

Let us understand the question and calculate the mean of the continuous random variable X step-by-step.

We are given that X is a continuous random variable representing the measured temperature. The range of temperature is [0, 100] degrees Celsius, and its probability density function (PDF) is given by:

f ( x ) = 0.01 for 0 x 100

Since the probability density function is constant over the interval [0, 100], X follows a continuous uniform distribution, denoted as U(a, b), where the lower limit a = 0 and the upper limit b = 100.

The mean (or expected value) of a continuous random variable X with a probability density function f(x) is defined by the formula:

E [ X ] = - x f ( x ) d x

Since f(x) is non-zero only in the interval [0, 100], we can restrict the integration limits to this interval:

E [ X ] = 0 100 x 0.01 d x

We can factor out the constant 0.01 from the integral:

E [ X ] = 0.01 0 100 x d x

Now, evaluate the integral of x, which is equal to x2 / 2:

E [ X ] = 0.01 [ x 2 2 ] 0 100

Substitute the upper and lower limits of integration:

E [ X ] = 0.01 ( 100 2 2 - 0 2 2 )

E [ X ] = 0.01 ( 10000 2 )

E [ X ] = 0.01 5000

E [ X ] = 50.0

Alternatively, since X is uniformly distributed on the interval [a, b], we can use the formula for the mean of a uniform distribution:
Mean = (a + b) / 2
Mean = (0 + 100) / 2 = 50.0.

Therefore, the mean of X is indeed 50.0.

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