Problem 3) A box contains four 40-W, five 60-W, and 6 75-W light bulbs. If bulbs are selected one by one in random order, what is the probability that at least two bulbs should be selected to obtain one that is rated 75-W?

Holt Mcdougal Larson Pre-algebra: Student Edition 2012
1st Edition
ISBN:9780547587776
Author:HOLT MCDOUGAL
Publisher:HOLT MCDOUGAL
Chapter11: Data Analysis And Probability
Section11.8: Probabilities Of Disjoint And Overlapping Events
Problem 2C
Question

need help with following

### Problem 3)

A box contains four 40-W, five 60-W, and six 75-W light bulbs. If bulbs are selected one by one in random order, what is the probability that at least two bulbs should be selected to obtain one that is rated 75-W?

---

To solve this problem, we need to determine the probability of selecting at least two bulbs in order to get one that is 75-W rated. The key is to calculate the complementary probability that the first selected bulb is not 75-W and then subtract that from 1.

Let's define:
- \( P(\text{first bulb not 75-W}) \) = Probability that the first selected bulb is not 75-W.

There are a total of \( 4 (40-W) + 5 (60-W) + 6 (75-W) = 15 \) light bulbs. 

The probability that the first selected bulb is not 75-W is:
\[ P(\text{first bulb not 75-W}) = \frac{4 + 5}{15} = \frac{9}{15} = \frac{3}{5} \]

The probability that the first selected bulb is a 75-W bulb is:
\[ P(\text{first bulb is 75-W}) = \frac{6}{15} = \frac{2}{5} \]

Now, we are interested in the complementary event that we do not get a 75-W bulb on the first draw. So the probability of getting at least one 75-W bulb in two draws (at least two bulbs need to be selected) is given by:
\[ P(\text{at least two bulbs selected to get 75-W}) = 1 - P(\text{first bulb is 75-W}) = 1 - \frac{2}{5} = \frac{3}{5} \]

Therefore, the probability that at least two bulbs should be selected to obtain one that is rated 75-W is \( \frac{3}{5} \) or 60%.

This approach illustrates the basic principles of probability relevant to randomly choosing objects and calculating the likelihood of specific outcomes in a sequence of draws.
Transcribed Image Text:### Problem 3) A box contains four 40-W, five 60-W, and six 75-W light bulbs. If bulbs are selected one by one in random order, what is the probability that at least two bulbs should be selected to obtain one that is rated 75-W? --- To solve this problem, we need to determine the probability of selecting at least two bulbs in order to get one that is 75-W rated. The key is to calculate the complementary probability that the first selected bulb is not 75-W and then subtract that from 1. Let's define: - \( P(\text{first bulb not 75-W}) \) = Probability that the first selected bulb is not 75-W. There are a total of \( 4 (40-W) + 5 (60-W) + 6 (75-W) = 15 \) light bulbs. The probability that the first selected bulb is not 75-W is: \[ P(\text{first bulb not 75-W}) = \frac{4 + 5}{15} = \frac{9}{15} = \frac{3}{5} \] The probability that the first selected bulb is a 75-W bulb is: \[ P(\text{first bulb is 75-W}) = \frac{6}{15} = \frac{2}{5} \] Now, we are interested in the complementary event that we do not get a 75-W bulb on the first draw. So the probability of getting at least one 75-W bulb in two draws (at least two bulbs need to be selected) is given by: \[ P(\text{at least two bulbs selected to get 75-W}) = 1 - P(\text{first bulb is 75-W}) = 1 - \frac{2}{5} = \frac{3}{5} \] Therefore, the probability that at least two bulbs should be selected to obtain one that is rated 75-W is \( \frac{3}{5} \) or 60%. This approach illustrates the basic principles of probability relevant to randomly choosing objects and calculating the likelihood of specific outcomes in a sequence of draws.
Expert Solution
trending now

Trending now

This is a popular solution!

steps

Step by step

Solved in 3 steps with 1 images

Blurred answer
Knowledge Booster
Anova and Design of Experiments
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, probability and related others by exploring similar questions and additional content below.
Recommended textbooks for you
Holt Mcdougal Larson Pre-algebra: Student Edition…
Holt Mcdougal Larson Pre-algebra: Student Edition…
Algebra
ISBN:
9780547587776
Author:
HOLT MCDOUGAL
Publisher:
HOLT MCDOUGAL
College Algebra
College Algebra
Algebra
ISBN:
9781337282291
Author:
Ron Larson
Publisher:
Cengage Learning
Algebra & Trigonometry with Analytic Geometry
Algebra & Trigonometry with Analytic Geometry
Algebra
ISBN:
9781133382119
Author:
Swokowski
Publisher:
Cengage
College Algebra (MindTap Course List)
College Algebra (MindTap Course List)
Algebra
ISBN:
9781305652231
Author:
R. David Gustafson, Jeff Hughes
Publisher:
Cengage Learning
Algebra and Trigonometry (MindTap Course List)
Algebra and Trigonometry (MindTap Course List)
Algebra
ISBN:
9781305071742
Author:
James Stewart, Lothar Redlin, Saleem Watson
Publisher:
Cengage Learning
College Algebra
College Algebra
Algebra
ISBN:
9781305115545
Author:
James Stewart, Lothar Redlin, Saleem Watson
Publisher:
Cengage Learning