Answer: $0.58
<u>Step-by-step explanation:</u>
Let x represent pencil and y represent eraser
10x + 7y = 4.23 → 1(10x + 7y = 4.23) → 10x + 7y = 4.23
3x + y = 0.95 → -3(3x + y = 0.95) → <u>-21x - 7y</u> =<u> -6.65 </u>
-11x = -2.42
<u>÷-11 </u> <u>÷-11 </u>
x = 0.22
3x + y = 0.95
3(0.22) + y = 0.95
0.66 + y = 0.95
y = 0.29
2y = 2(0.29) = 0.58
Answer:
The 95% confidence interval for the proportion of all boards in this shipment that fall outside the specification is (1.8%, 6.2%).
Step-by-step explanation:
Let <em>X</em> = number of boards that fall outside the most rigid level of industry performance specifications.
In a random sample of 300 boards the number of defective boards was 12.
Compute the sample proportion of defective boards as follows:

The (1 - <em>α</em>)% confidence interval for population proportion <em>p</em> is:

The critical value of <em>z</em> for 95% confidence level is,

*Use a <em>z</em>-table.
Compute the 95% confidence interval for the proportion of all boards in this shipment that fall outside the specification as follows:

Thus, the 95% confidence interval for the proportion of all boards in this shipment that fall outside the specification is (1.8%, 6.2%).