Binomial averages, the Central Limit Theorem and the normal curve

Answer Key - Grade 11 Math Worksheet - Challenge Me

Circle the best answer, or write your answer on the line.

1. 1.

   Kira wants P(X ≥ 60) for heads in 100 coin flips. Counts are whole numbers, so the normal curve needs a half-unit edge. What x-value marks the edge of that area?

   • 60
   • 60.5
   • 59.5
2. 2.

   Luz wants P(X ≤ 40) for blue spins out of 120. Counts are whole numbers, so the normal curve needs a half-unit edge. What x-value marks the edge of that area?

   • 39.5
   • 40
   • 40.5
3. 3.

   Milo wants P(X > 60) for sprouting seeds out of 75. Counts are whole numbers, so the normal curve needs a half-unit edge. What x-value marks the edge of that area?

   • 59.5
   • 60
   • 60.5
4. 4.

   Ren wants P(X < 40) for made shots out of 64. Counts are whole numbers, so the normal curve needs a half-unit edge. What x-value marks the edge of that area?

   • 40.5
   • 40
   • 39.5
5. 5.

   Tala spins a spinner 625 times: mean 125 reds, standard deviation 10. With the 68–95–99.7 rule, about what percent of runs give more than 145?

   2.5
6. 6.

   Zee's school flips 900 coins: mean 450 heads, standard deviation 15. With the 68–95–99.7 rule, about what percent of runs give fewer than 435?

   16
7. 7.

   Bo guesses on 100 true-false questions: mean 50 right, standard deviation 5. With the 68–95–99.7 rule, about what percent of runs give more than 55?

   16
8. 8.

   Sunflower heights have standard deviation 20 cm. Jun wants the sample mean's standard deviation to be 4 cm. How many values should each sample have?

   25
9. 9.

   Rice bag weights have standard deviation 30 g. Kira wants the sample mean's standard deviation to be 3 g. How many values should each sample have?

   100
10. 10.

    Bus waits have standard deviation 9 minutes. Luz wants the sample mean's standard deviation to be 1.5 minutes. How many values should each sample have?

    36