Math Problem Statement

Use the data in the following​ table, which lists​ drive-thru order accuracy at popular fast food chains. Assume that orders are randomly selected from those included in the table.

​Drive-thru Restaurant   

A

B

C

D

Order Accurate

327327

277277

2492\49138138

Order Not Accurate A.39 B. 53 C. 37 D. 14If two orders are​ selected, find the probability that they are both from Restaurant D.

a. Assume that the selections are made with replacement. Are the events​ independent?

b. Assume that the selections are made without replacement. Are the events​ independent?

Solution

Let's first analyze the given data to clarify the problem.

Data Table:

RestaurantABCD
Order Accurate327277249138
Order Not Accurate39533714

From this table, we can calculate the total number of orders for each restaurant:

  • Restaurant A: 327+39=366327 + 39 = 366
  • Restaurant B: 277+53=330277 + 53 = 330
  • Restaurant C: 249+37=286249 + 37 = 286
  • Restaurant D: 138+14=152138 + 14 = 152

The total number of orders for all restaurants is: 366+330+286+152=1134366 + 330 + 286 + 152 = 1134

Part (a): Selections Made with Replacement

When selections are made with replacement, the selections are independent. The probability of each event does not change based on previous events.

To find the probability that both selected orders are from Restaurant D:

  1. The probability that the first order is from Restaurant D is: P(1st order from D)=1521134P(\text{1st order from D}) = \frac{152}{1134}
  2. The probability that the second order is also from Restaurant D (since the events are independent): P(2nd order from D)=1521134P(\text{2nd order from D}) = \frac{152}{1134}
  3. The probability that both orders are from Restaurant D is: P(both orders from D)=(1521134)×(1521134)=152211342=2310412859560.01797P(\text{both orders from D}) = \left( \frac{152}{1134} \right) \times \left( \frac{152}{1134} \right) = \frac{152^2}{1134^2} = \frac{23104}{1285956} \approx 0.01797

Thus, the probability that both orders are from Restaurant D when selections are made with replacement is approximately 0.01797.

Part (b): Selections Made without Replacement

When selections are made without replacement, the selections are dependent, because the probability for the second selection changes depending on the first.

To find the probability that both selected orders are from Restaurant D:

  1. The probability that the first order is from Restaurant D is the same: P(1st order from D)=1521134P(\text{1st order from D}) = \frac{152}{1134}
  2. However, if the first order is from Restaurant D, there is now one fewer order from Restaurant D and one fewer total order, so the probability for the second order being from Restaurant D is: P(2nd order from D)=1511133P(\text{2nd order from D}) = \frac{151}{1133}
  3. The probability that both orders are from Restaurant D is: P(both orders from D)=1521134×1511133=152×1511134×1133=2295212851580.01786P(\text{both orders from D}) = \frac{152}{1134} \times \frac{151}{1133} = \frac{152 \times 151}{1134 \times 1133} = \frac{22952}{1285158} \approx 0.01786

Thus, the probability that both orders are from Restaurant D when selections are made without replacement is approximately 0.01786.

Summary of Answers:

  • a. The probability of both orders being from Restaurant D when selections are made with replacement is approximately 0.01797. The events are independent.
  • b. The probability of both orders being from Restaurant D when selections are made without replacement is approximately 0.01786. The events are dependent.

Would you like more details, or do you have any questions?

Here are 5 follow-up questions for further exploration:

  1. What is the probability of selecting one accurate and one inaccurate order from Restaurant D with replacement?
  2. How does the probability of selecting two orders from Restaurant A compare to Restaurant D?
  3. What is the probability of selecting exactly one order from Restaurant B and one from Restaurant C without replacement?
  4. How does the probability change if we select three orders instead of two?
  5. What is the total probability of selecting accurate orders for all restaurants combined?

Tip: When working with probabilities involving replacement, remember that the key factor is whether or not the total number of available outcomes changes after each selection!

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Math Problem Analysis

Mathematical Concepts

Probability
Independent and Dependent Events
Combinatorics

Formulas

P(both orders from D with replacement) = (152 / 1134) * (152 / 1134)
P(both orders from D without replacement) = (152 / 1134) * (151 / 1133)

Theorems

Multiplication Rule of Probability

Suitable Grade Level

Grades 9-11