What are the chances?

The probability that Billy is late to school on any given random day is 0.4. The probability that he is early is 0.25.

Out of 160 school days, on how many days would you expect him to arrive just on time?

• 40

• 56

• 66

• 80

Tags

CCSS.7.SP.C.6

What is the probability that you will get this question wrong?

• Certain

• Likely

• Even Chance

• Unlikely

• Impossible

Tags

CCSS.7.SP.C.5

Angela rolls two fair dice and multiplies the two scores to get a result. What is the probability that the result is a multiple of 4?

• 1/6

• 5/36

• 5/12

• 1/9

What does it mean if a dice is 'fair'?

• It does not cheat.

• The person who rolls it does not cheat.

• Each outcome is random.

• Each outcome is equally likely.

Tags

CCSS.7.SP.C.7A

A game costs $1 to play. In the game, two dice are rolled. A total of nine on the two dice results in a prize of $17.

What is the expected amount of money you would win if you played this game 100 times?

• $0

• $68

• -$32 (minus)

• $512

Tags

CCSS.HSS.MD.B.5A

If you randomly pick an answer to this question, what is the probability that you will get it right?

• 0.25

• 0.25

• 0.5

• My head hurts

Five coins are flipped. Any coins that land heads up are flipped again. What is the probability that all of the coins are now heads down?

• Zero

• Less than even

• Even

• Greater than even

• Certain

Tags

CCSS.7.SP.C.5

You are presented with a red envelope and a blue envelope. You are told that one of the envelopes contains twice as much money as the other.

You randomly pick the red envelope, open it, and find $100 dollars inside. You are then invited to switch to the other (blue) envelope without looking at what it contains.

Select the statement below which most accurately describes what you should now do.

• Stick with the $100. Switching makes no difference.

• Switch to the blue envelope because it may contain $200. If it does, you'd win $100 more. If it doesn't, you'd only lose $50. Since your original choice was a 50-50 thing, you stand to gain more money (on average) by switching.

Tags

CCSS.HSS.MD.B.6

CCSS.HSS.MD.B.7

In Gumboland, the government wants to increase the number of girls.

A new law is passed. If a baby girl is born, the parents are not permitted to have any more children. If a boy is born, the parents can have another baby if they want to.

What effect will this plan have over time?

• The proportion of boys will increase.

• The ratio of boys and girls will remain roughly the same.

• The proportion of girls will increase.

Montgomery is standing on the edge of a cliff. It's very dangerous.

He flips a fair coin repeatedly an infinite number of times. When it shows a head, he moves one metre away from the cliff edge.

When it shows a tail, however, he moves 1cm back towards the cliff edge.

Which of the following is true?

• He is perfectly safe. He can never end up moving off the cliff edge.

• He is fairly safe. It is unlikely that he will ever move off the cliff edge.

• He is extremely unsafe. It is likely he will eventually move off the cliff edge.

• He is doomed. He will eventually move off the cliff edge.