Independent Events
A coin is flipped and then a number cube is rolled. What is the probability of getting heads and a 4?
1/2 x 1/6=1/12
A bag has 4 red and 6 blue marbles.
Two marbles are chosen without replacement.
What is the probability of choosing two red marbles?
4/10 x 3/9= 2/15
What is the theoretical probability of rolling a 6 on a number cube?
1/6
A coin is flipped 20 times and lands on heads 12 times.
What is the experimental probability of heads? give your answer in the simplest form
12/20 = 3/5
A spinner lands on blue 1 out of every 4 spins.
Out of 20 spins, how many times would you expect it to land on blue?
1/4 x 20=5
You spin a spinner with 5 equal sections numbered 1–5 and roll a die. What is the probability of landing on 3 and rolling an even number?
1/5 x 1/2 = 1/10
A bag has 5 green and 5 yellow marbles.
Two marbles are chosen without replacement.
What is the probability of choosing two green marbles?
5/10 x 4/9=20/90 or 2/9
What is the probability of selecting a vowel from the word PROBABILITY?
4/11
Which describes the probability of tossing a number less than 6 on a number cube with faces labeled 1-6?
A. impossible
B. unlikely
C. likely
D. certain
C. likely
A bag contains 2 red and 8 blue marbles.
If a marble is chosen and replaced 50 times, how many times would you expect to choose a red marble?
1/5x50=10
A card is drawn from a standard deck, replaced, then another card is drawn.
What is the probability of drawing a heart both times?
hearth 13/52 or 1/4
1/4 x 1/4 = 1/16
A box contains 6 pencils and 4 pens.
Two items are chosen without replacement.
What is the probability of choosing a pencil, then a pen?
6/10 x 4/9 = 4/15
A spinner has 8 equal sections, 3 are red.
What is the theoretical probability of landing on red?
3/8
A dice is rolled 60 times and lands on 5 9 times.
What is the experimental probability of rolling a 5?
9/60 = 3/20
A dice is rolled 120 times.
How many times would you expect to roll an even number?
3/6x120=60
You randomly choose a letter from the word MATH, replace it, and choose again.
What is the probability of choosing M both times?
1/4 x 1/4 = 1/16
A bag contains 3 red, 3 blue, and 4 green marbles.
Two marbles are chosen without replacement.
A student writes:
4/10 × 4/10=16/100
Question:
What mistake did the student make, and what is the correct probability of choosing two green marbles?
The student did not reduce the total or the number of green marbles after the first marble was chosen.
correct answer:
4/10 x 3/9
A bag has 4 red, 3 blue, and 5 green marbles.
What is the probability of choosing a marble that is NOT blue? give your answer in percentage
9/12 or 3/4 = 75%
A bag is sampled 50 times. A red marble is selected 22 times.
What is the experimental probability of selecting red?
Simplify your answer
22/50 = 11/25
The experimental probability of rain is 0.35.
Out of 40 days, about how many days would you expect rain?
0.35x40=14
A bag has 4 red, 6 blue, and 10 green marbles. One marble is chosen, replaced, and another is chosen.
What is the probability of choosing a blue marble both times?
blue 6/20 or 3/10
3/10 x 3/10 = 9/100
There are 8 students in a group: 5 girls and 3 boys.
Two students are chosen without replacement.
A student writes:
5/8 x 3/8 = 15/64
Question:
What mistake did the student make, and what is the correct probability of choosing a girl, then a boy?
The student treated the events as independent and did not adjust the number of students after the first selection.
Correct work:
5/8 x 3/7 =15/56
A number from 1–20 is chosen at random.
What is the probability that the number is a multiple of 3 or 5?
9/20 because they overlap with number 15, you only count it once !
A student records 120 spins of a spinner. It lands on yellow 45 times.
What is the experimental probability of landing on yellow? Give your answer in decimal form
45/120=0.375
3/8=0.375
A spinner lands on green 60% of the time.
If the spinner is spun 250 times, how many times should it land on green?
0.60x250=150