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Probability
Math
Middle School Math

 Name _____________________________ Date ___________________
Probability
Complete.

 1 Dylan lives in Montana. On a bus trip across the state he looks out the window and sees where other vehicles are from. On the trip he sees 125 vehicles with Montana plates and 40 with non-Montana plates. On the trip back the next day, what is the probability that the first car he sees is from Montana?
 2 Noah counts the grasshoppers in the garden on Monday. He finds nineteen big ones and nine small ones. On Tuesday he counts them again. This time he counts a total of eighty-seven grasshoppers. What is a reasonable prediction to make as to how many of the grasshoppers were large ones when he counted them on Tuesday?
 3 Mr. Bloop has discovered a new species of cactus in Bolivia. He goes to the location where they are found on the side of a mountain. He sees many specimens of the new species growing there. He collects some data on the color of the flowers produced by this cactus. He finds that thirty-five of the plants have purple flowers and sixteen have white flowers. Now, assuming that the flower color ratio is the same everywhere in Bolivia for this plant, if he goes to another mountain side and collects similar data, what is the probability that the first plant he comes across will have white flowers? Write your answer as a percent rounded to the nearest tenth.
 4 Last night, Christina counted the number of instant messages she received. She received four from Kyle, eleven from Christina, five from Steven, nine from Kevin, and twenty-four from her best friend (and very chatty) Natalie. She turned on her computer. What is the probability that the first instant message she receives is from Natalie?
 5 Kayla has taken twenty-nine math quizzes this year. Of those, she scored above 90% on five of them and 80% or above on fourteen of them. What is the probability that she will score from 80% to 90% on her next math quiz?
 6 Isaac and William go to the mall parking lot on weekends to see if they can find any loose change. People tend to lose small amounts of money in the parking lot. Over the past year they have kept track of how much money they have found. They found eleven quarters, three fifty-cent pieces, thirty-six dimes, forty nickels, and one hundred thirty-four pennies. What is the probability that the next coin they find will be worth more than ten cents? State your answer as a percent to the nearest percent.

Sample
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