A college student is preparing a course schedule for the next semester. The student must select one of three mathematics courses
1 answer:
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<h3>Key points :-</h3>
✪ Both triangles will be proven similar by AA theorem i.e. Angle-Angle theorem.
✪ The symbol for similarity is ~.
✪ The symbol for congruency is ≅.
- <em>D</em><em>e</em><em>t</em><em>a</em><em>i</em><em>l</em><em>e</em><em>d</em><em> </em><em>s</em><em>o</em><em>l</em><em>u</em><em>t</em><em>i</em><em>o</em><em>n</em><em> </em><em>i</em><em>s</em><em> </em><em>a</em><em>t</em><em>t</em><em>a</em><em>c</em><em>h</em><em>e</em><em>d</em><em>!</em><em>!</em>
Answer:
(a) P(X 20) = 0.9319
(b) Expected number of defective light bulbs = 15
Step-by-step explanation:
We are given that a manufacturer of Christmas light bulbs knows that 10% of these bulbs are defective. It is known that light bulbs are defective independently. A box of 150 bulbs is selected at random.
Firstly, the above situation can be represented through binomial distribution, i.e.;
where, n = number of samples taken = 150
r = number of success
p = probability of success which in our question is % of bulbs that
are defective, i.e. 10%
<em>Now, we can't calculate the required probability using binomial distribution because here n is very large(n > 30), so we will convert this distribution into normal distribution using continuity correction.</em>
So, Let X = No. of defective bulbs in a box
<u>Mean of X</u>, =
=
= 15
<u>Standard deviation of X</u>, =
=
= 3.7
So, X ~ N(
Now, the z score probability distribution is given by;
Z = ~ N(0,1)
(a) Probability that this box will contain at most 20 defective light bulbs is given by = P(X 20) = P(X < 20.5) ---- using continuity correction
P(X < 20.5) = P( <
) = P(Z < 1.49) = 0.9319
(b) Expected number of defective light bulbs found in such boxes, on average is given by = E(X) = =
= 15.