A manufacturer of electronic calculators offers a one-year warranty. If the calculator fails for any reason during this period, it is replaced. The time to failure is well modeled by the following probability distribution: f(x) = 0.125e^-0.125x x > 0
(a) What percentage of the calculators will fail within the warranty period?
(b) The manufacturing cost of a calculator is $50, and the profit per sale is $25. What is the effect of warranty replacement on profit?

Respuesta :

Answer:

(a) 11.75%

(b) Profit decreases by $5.88 per calculator.

Step-by-step explanation:

(a) The percentage of failures with time is given by the following expression:

[tex]f(x) = 0.125*e^{-0.125x}[/tex]

Integrating this function from x = 0 to x = 1 year, gives us the percentage of failures in the first year:

[tex]\int\limits^1_0 {f(x)} \, dx = F(x)=-e^{-0.125x}|_0^1\\F(1) = -e^{-0.125*1}-(-e^{-0.125*0}) = 1-e^{-0.125}\\F(1) =0.1175[/tex]

11.75% of the calculators will fail within the warranty period.

(b) If the cost of a calculator is $50, and the profit per sale is $25, the average revenue per calculator is $75. Considering no income in failed calculators, the new cost per calculator is:

[tex]C =\$50*(1+0.1175)\\C=\$55.88[/tex]

The effect of warranty replacement on profit is given by the difference in cost per calculator:

[tex]\Delta P= \$50-\$55.88=-\$5.88[/tex]

Profit decreases by $5.88 per calculator.

The percentage that fails within the warranty period is 11.75%, and the effect of warranty replacement on profit is a decrease in profit

The percentage that fails within the warranty period

The probability distribution function is given as:

[tex]f(x) = 0.125e^{-0.125x}[/tex], x > 0

The warranty is one year.

So, the percentage of the calculators that will fail within the warranty period must fall within 0 to 1 year.

This is represented as:

[tex]F(x) = \int\limits^1_0 {f(x)} \, dx[/tex]

This gives

[tex]F(x) = \int\limits^1_0 {0.125e^{-0.125x}} \, dx[/tex]

Factor out 0.125

[tex]F(x) = 0.125 \int\limits^1_0 {e^{-0.125x}} \, dx[/tex]

Integrate

[tex]F(x) = \frac{0.125}{0.125}* [-{e^{-0.125x}]|\limits^1_0[/tex]

This gives

[tex]F(x) = [-{e^{-0.125x}]|\limits^1_0[/tex]

Expand

[tex]F(x) = -e^{-0.125(1)} +e^{-0.125(0)[/tex]

[tex]F(x) = -e^{-0.125(1)} +1[/tex]

Solve the expression

[tex]F(x) = 0.1175[/tex]

Express as percentage

[tex]F(x) = 11.75\%[/tex]

The effect of the warranty

The manufacturing cost of a calculator is $50, and the profit per sale is $25.

So, we have the new cost (C) to be:

[tex]C = 50 + 50 * 11.75\%[/tex]

[tex]C = 55.875[/tex]

Calculate the change in cost

[tex]\Delta C = 50 - 55.875[/tex]

[tex]\Delta C = - 5.875[/tex]

-5.875 is less than 0.

Hence, the effect of warranty replacement on profit is a decrease in profit

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