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Information on a packet of seeds claims that the germination rate is \(92 \% .\) What's the probability that more than \(95 \%\) of the 160 seeds in the packet will germinate? Be sure to discuss your assumptions and check the conditions that support your model.

Short Answer

Expert verified
The probability is 7.64%.

Step by step solution

01

Understand the Scenario

We have a packet of seeds with a claimed germination rate of 92%. We need to determine the probability that more than 95% of these seeds will germinate. The total number of seeds is 160.
02

Set Up the Model

The problem describes a binomial scenario where each seed has a 92% chance of germinating. This can be modeled using a binomial distribution, where the number of trials, \(n = 160\), and the probability of success, \(p = 0.92\).
03

Check the Normal Approximation Conditions

For a binomial distribution, we can use a normal approximation if both \(n \times p\) and \(n \times (1-p)\) are greater than 5. Here, \(n \times p = 160 \times 0.92 = 147.2\) and \(n \times (1-p) = 160 \times 0.08 = 12.8\), both of which are greater than 5. Hence, the normal approximation is reasonable.
04

Define the Normal Distribution

Using the normal approximation, define a normal distribution with mean \(\mu = n \times p = 147.2\) and standard deviation \(\sigma = \sqrt{n \times p \times (1-p)} = \sqrt{160 \times 0.92 \times 0.08} = 3.36\).
05

Calculate the Z-score

We want to find the probability of more than 95% germination success, which means more than 152 seeds (since 95% of 160 is 152). Calculate the Z-score using \(Z = \frac{152 - 147.2}{3.36} = 1.43\).
06

Use the Z-score to Find Probability

Look up the Z-score of 1.43 in the standard normal distribution table to find the probability. The Z-score table gives a value of 0.9236. However, this is the probability of \(Z < 1.43\), so the probability of \(Z > 1.43\) is \(1 - 0.9236 = 0.0764\).
07

Interpret the Result

Therefore, the probability that more than 95% of the seeds will germinate is 0.0764, or 7.64%.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Probability
Probability is a way to measure the likelihood of a particular outcome. In our exercise, we're dealing with the probability that more than 95% of the seeds in a packet will germinate. If the packet states the germination rate is 92%, it means for any one seed, there's a 92% chance it will sprout. In simple terms, if there were just one seed, you'd expect it to germinate most of the time, but not always. With 160 seeds, probability becomes more interesting because the number of seeds significantly boosts the chance calculations. The probability of an event occurring is always between 0 and 1, where 0 means it will never happen, and 1 means it will certainly happen. When we say the germination rate is 92%, we're dealing with a probability of 0.92 for each seed.
Normal Approximation
Normal approximation is a handy statistical tool for estimating probabilities of a binomial distribution when calculations become complex with large sample sizes. Essentially, it lets us use a normal distribution, which is simpler, to approximate a binomial distribution.For this approximation to work well, two conditions must be met: both the number of successes, given by \(n \times p\), and the number of failures, given by \(n \times (1-p)\), need to be greater than 5. In the exercise, with 160 seeds and a success rate of 92%, we calculated \(n \times p = 147.2\) and \(n \times (1-p) = 12.8\). Since both values are greater than 5, the normal approximation is justified.Using normal approximation simplifies our calculations and helps us find probabilities for more complex scenarios that would be cumbersome with pure binomial calculations.
Z-score
The Z-score is a statistical measurement that describes a value's position in relation to the mean of a group of values. When working with normal distributions, Z-scores can help quickly find the probability of a particular outcome.In the exercise, the Z-score formula was used to calculate how far 152 seeds is from the average number, 147.2, based on standard normal distribution principles. The formula used is:\[ Z = \frac{X - \mu}{\sigma} \]where \(X\) is the number of seeds we are interested in, 152; \(\mu\) is the mean, 147.2; and \(\sigma\) is the standard deviation, 3.36. This calculates to a Z-score of 1.43.A positive Z-score indicates the value is above the mean, and this can be looked up in a standard normal distribution table to find the probability of that event occurring.
Germination Rate
The germination rate is a measure of the number of seeds that successfully sprout compared to the total number planted. It's an important concept in agriculture and planting, as it helps farmers and gardeners predict yield and plan accordingly. For the package of seeds mentioned in our exercise, the germination rate is given as 92%. This means, on average, you would expect 92 out of every 100 seeds to germinate. However, not every batch of seeds will have exactly 92% success due to variability and random chance. Understanding germination rates and their implications is crucial when assessing planting success. Knowing this rate allows for improved planning and prediction of resources needed, and helps gauge whether a reported germination rate is accurate based on observed outcomes. In our problem, calculating whether more than 95% of seeds will germinate involves finding a probability based on this rate.

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Most popular questions from this chapter

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