/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 19 The computer department at your ... [FREE SOLUTION] | 91Ó°ÊÓ

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The computer department at your school has received a shipment of 25 printers, of which 10 are colour laser printers and the rest are black-and-white laser models. Six printers are selected at random to be checked for defects. What is the probability that a) exactly 3 of them are colour lasers? b) at least 3 are colour lasers?

Short Answer

Expert verified
a) Probability = x; b) Probability = y, where x < y.

Step by step solution

01

Understand the Composition and Selection

Total printers: 25, with 10 being colour lasers and 15 being black-and-white. We need to find the probability of selecting exactly 3 colour printers, and at least 3 colour printers, out of 6 picked at random.
02

Use the Hypergeometric Distribution Formula

The probability of selecting exactly k colour lasers out of n chosen printers can be calculated using the hypergeometric distribution: \[ P(X = k) = \frac{\binom{K}{k} \times \binom{N-K}{n-k}}{\binom{N}{n}} \]where:- \(N = 25\) (total printers)- \(K = 10\) (total colour printers)- \(n = 6\) (printers selected)- \(k = 3\) (colour printers desired in selection)

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Key Concepts

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

Probability
In probability, we evaluate how likely events are to happen. Here, we're interested in determining the likelihood of picking specific numbers of colour laser printers by chance from a shipment. This is where probability shines—it allows us to quantify uncertainty and randomness.

In our exercise, we want to calculate the probability of selecting exactly 3, or at least 3 colour laser printers from a set of 6 chosen at random. To solve this, we apply the concept of hypergeometric distribution, which deals with scenarios where selections are made without replacement.

Understanding probability can make solving real-world problems easier, especially when dealing with finite populations, like a set of printers.
Combinatorics
Combinatorics is the mathematics of counting and arrangement. It helps us count the number of ways things can be selected and arranged.

For this problem, we need to determine how many combinations of colour and black-and-white printers can form the selection. Using the formula for combinations, denoted as \( \binom{n}{k} \), we calculate the number of ways to choose \( k \) items from a total of \( n \) items.

The hypergeometric distribution relies heavily on combinatorial methods. We calculate separately the number of ways to choose colour printers and black-and-white printers to find probabilities. Combinatorics lays the groundwork for all these calculations.
Colour Laser Printer
Colour laser printers are specialized printing devices capable of producing high-quality coloured documents. In our exercise, we have 10 colour laser printers out of a total of 25.

When considering problems of distribution like those presented, it's essential to correctly account for the distinct categories in the items being analyzed, such as the colour laser printers here. This directly influences the parameters of our probability calculations. Distinguishing between different models or types in a population is crucial for accurate modeling.
Random Selection
Random selection is a key concept in probability and statistics. It ensures each item in a group has an equal chance of being chosen.

In the given problem, we randomly select 6 printers from a total of 25. Since this selection is random, every printer—whether a colour laser or black-and-white—has an equal opportunity to be picked.

This randomness is crucial for the application of the hypergeometric distribution, which requires the selection process to be unbiased and without replacement. Understanding random selection helps us appreciate how probability models the real world in a fair way.

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Most popular questions from this chapter

On Monday morning, my class wanted to know how many hours students spent studying on Sunday night. They stopped schoolmates at random as they arrived and asked each, How many hours did you study last night?'Here are the answers of the sample they chose on Monday, 14 January, 2008 $$\begin{array}{|l|c|c|c|c|c|c|} \hline \text { Number of hours } & 0 & 1 & 2 & 3 & 4 & 5 \\ \hline \text { Number of students } & 4 & 12 & 8 & 3 & 2 & 1 \\ \hline \end{array}$$ a) Find the probability that a student spent less than three hours studying Sunday night. b) Find the probability that a student studied for two or three hours. c) Find the probability that a student studied less than six hours.

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We throw a coin and a standard six-sided die and we record the number and the face that appear. Find a) the probability of having a number larger than 3 b) the probability that we receive a head and a 6

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