Each question Sandra answers incorrectly changes her overall score by -3/4 points. Sandras overall score was -4 1/2 points , and
1 answer:
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Answer:
(a) The probability distribution is valid.
(b) The probability that x = 30 is 0.30.
Step-by-step explanation:
The probability distribution of the random variable <em>X</em> is:
<em> x</em>: 20 | 25 | 30 | 35
f (<em>x</em>): 0.20 | 0.15 | 0.30 | 0.35
(a)
The properties of a probability distribution are:
- 0 ≤ P (X) ≤ 1
- ∑ P (X) = 1
All the probability value are more than 0 and less than 1.
Compute the sum of all the probabilities as follows:
The sum of all probabilities is 1.
Thus, the probability distribution is valid.
(b)
Consider the probability distribution table.
The probability of <em>X</em> = 30 is,
P (X = 30) = 0.30.
Thus, the probability that x = 30 is 0.30.