Answer:520; 240
Step-by-step explanation:
a. 13, 26, 39, 52,......
a = First term = 13
d = common difference = 26 - 13 = 13
40th term = a + (n - 1)d = a + (40-1)d = a + 39d
= 13 + (39 × 13)
= 13 + 507
= 520
b. 6, 12, 18, 24,.......
a = First term = 6
d = common difference = 12 - 6 = 6
40th term = a + 39d
= 6 + 39(6)
= 6 + 234.
= 240
Using the normal distribution, it is found that there is a 0.877 = 87.7% probability of a bulb lasting for at most 569 hours.
<h3>Normal Probability Distribution</h3>
The z-score of a measure X of a normally distributed variable with mean
and standard deviation
is given by:

- The z-score measures how many standard deviations the measure is above or below the mean.
- Looking at the z-score table, the p-value associated with this z-score is found, which is the percentile of X.
The mean and the standard deviation are given, respectively, by:

The probability of a bulb lasting for at most 569 hours is the <u>p-value of Z when X = 569</u>, hence:


Z = 1.16
Z = 1.16 has a p-value of 0.877.
0.877 = 87.7% probability of a bulb lasting for at most 569 hours.
More can be learned about the normal distribution at brainly.com/question/24663213
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Answer:
0.8c
Step-by-step explanation:
Answer: 200 bulbs will not be defective.
Step-by-step explanation:
The ratio of defective bulbs to good bulbs produced each day is 2 to 10. This ratio can also be expressed as 1 to 5 by reducing to lowest terms.
The total ratio is the sum of the proportions.
Total ratio = 1 + 5 = 6
This means that if n bulbs is produced, the number of defective bulbs would be
1/6 × n
The number of non defective would be
5/6 × n
Since n = 240, then the number of bulbs that will not be defective is
5/6 × 240 = 200 bulbs