Average reading score is given by the expression,
y = 0.153x + 255.4
Here, x in the number of years past 1970.
To find the year in which the average reading score is 259.378, substitute the value of 'y' in the given expression.
y = 0.153x + 255.4
259.378 = 0.153(x) + 255.4
0.153x = 259.378 - 255.4
0.153x = 3.978
x =
x = 26
That means given average reading score 259.378 will be 26 years after 1970.
Therefore, 1996 is the year in which the average reading score will be 259.378.
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Answer:
(a) The probability that <em>Y</em>₂₀ exceeds 1000 is 3.91 × 10⁻⁶.
(b) <em>n</em> = 28.09
Step-by-step explanation:
The random variable <em>Y</em>ₙ is defined as the total numbers of dollars paid in <em>n</em> years.
It is provided that <em>Y</em>ₙ can be approximated by a Gaussian distribution, also known as Normal distribution.
The mean and standard deviation of <em>Y</em>ₙ are:
(a)
For <em>n</em> = 20 the mean and standard deviation of <em>Y</em>₂₀ are:
Compute the probability that <em>Y</em>₂₀ exceeds 1000 as follows:
**Use a <em>z </em>table for probability.
Thus, the probability that <em>Y</em>₂₀ exceeds 1000 is 3.91 × 10⁻⁶.
(b)
It is provided that P (<em>Y</em>ₙ > 1000) > 0.99.
The value of <em>z</em> for which P (Z < z) = 0.01 is 2.33.
Compute the value of <em>n</em> as follows:
The last equation is a quadratic equation.
The roots of a quadratic equation are:
a = 16
b = -805.4289
c = 10000
On solving the last equation the value of <em>n</em> = 28.09.