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Sep 11, 2023
Sep 10, 2023
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There are two ways to solve this problem.

 

Method 1: Using complementary counting

We can solve this problem by finding the number of ways in which no flavor is selected by exactly three children and subtracting from the total number of ways in which the children can choose their ice cream flavors.

The total number of ways in which the children can choose their ice cream flavors is 36=729.

There are three ways to choose which flavor will be selected by exactly three children. Once we have chosen the flavor, we can assign it to any three children in (36​)=20 ways.

The remaining three children will each have 2 choices for their ice cream flavor. So the total number of ways in which no flavor is selected by exactly three children is 3×20×23=540.

Therefore, the number of ways in which some flavor of ice cream is selected by exactly three children is 729−540=189​.

 

Method 2: Using casework

We can also solve this problem by considering the three cases where the flavor selected by exactly three children is:

The chocolate flavor.

The vanilla flavor.

The strawberry flavor.

In each case, we can count the number of ways to choose the three children who will get that flavor and the number of ways to choose the flavors for the remaining three children.

The total number of ways is then the sum of the number of ways in each case.

The casework is as follows:

Case 1: The chocolate flavor.

There are (36​)=20 ways to choose the three children who will get chocolate. The remaining three children can each choose from the two remaining flavors, so there are 23=8 ways to choose their flavors.

Case 2: The vanilla flavor.

The number of ways is the same as in Case 1.

Case 3: The strawberry flavor.

The number of ways is the same as in Case 1.

Therefore, the total number of ways is 20×8+20×8+20×8=189.

Sep 10, 2023
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Sep 10, 2023
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I need help with these problems too.  Please solve these!

 

1. You draw one card from a standard deck of playing cards. If you pick a heart, you will win $10. If you pick a face card, which is not a heart, you win $8. If you pick any other card, you lose $6. Do you want to play? Explain.

 

2. The world famous gambler from Philadelphia, Señor Rick, proposes the following game of chance. You roll a fair die. If you roll a 1, then Señor Rick pays you $25. If you roll a 2, Señor Rick pays you $5. If you roll a 3, you win nothing. If you roll a 4 or a 5, you must pay Señor Rick $10, and if you roll a 6, you must pay Señor Rick $15. Is Señor Rick loco for proposing such a game? Explain.

 

3. You pay $10 to play the following game of chance. There is a bag containing 12 balls, five are red, three are green and the rest are yellow. You are to draw one ball from the bag. You will win $14 if you draw a red ball and you will win $12 is you draw a yellow ball. How much do you expect to win or loss if you play this game 100 times?

 

4. A detective figures that he has a one in nine chance of recovering stolen property. His outof-pockets expenses for the investigation are $9,000. If he is paid his fee only if he recovers the stolen property, what should he charge clients in order to breakeven?

 

5 At Tucson Raceway Park, your horse, Soon-to-be-Glue, has a probability of 1/20 of coming in first place, a probability of 1/10 of coming in second place, and a probability of ¼ of coming in third place. First place pays $4,500 to the winner, second place $3,500 and third place $1,500. Is it worthwhile to enter the race if it costs $1,000?

 

6. Your company plans to invest in a particular project. There is a 35% chance that you will lose $30,000, a 40% chance that you will break even, and a 25% chance that you will make $55,000. Based solely on this information, what should you do?

 

7. A manufacturer is considering the manufacture of a new and better mousetrap. She estimates the probability that the new mousetrap is successful is 3 4 . If it is successful it would generate profits of $120,000. The development costs for the mousetrap are $98,000. Should the manufacturer proceed with plans for the new mousetrap? Why or why not?

 

8. A grab bag contains 12 packages worth 80 cents apiece, 15 packages worth 40 cents apiece and 25 packages worth 30 cents apiece. Is it worthwhile to pay 50 cents for the privilege of picking one of the packages at random?

Sep 10, 2023

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