Question

A coin is flipped four times. X is the number of times it will land with a head up.

Which statement is true about this situation?

The variable X has a binomial distribution. P(success)=0.5P(success)=0.5; number trials = 4

The variable X does not have a binomial distribution because P(success) is not constant.

The variable X does not have a binomial distribution because there are more than two possible outcomes.

The variable X has a binomial distribution. P(success)=0.25; number of trials = 4

Answer 1

hint: what is the probability of heads on ONE coin?

Answer 2

0.5?

Answer 3

good

so P(success) = 0.5

since there are two outcomes, this is a binomial distribution with number of trials = 4

so option A must be your answer

Answer 4

can you help with more please?

Answer 5

ok

Answer 6

For a certain type of hay fever, Medicine H has a 30% probability of working.

In which distributions does the variable X have a binomial distribution?

Select each correct answer.



When the medicine is tried with two patients, X is the number of doses each patient needs to take.

When the medicine is tried with six patients, X is the number of patients for whom the medicine does not work.

When the medicine is tried with two patients, X is the number of patients for whom the medicine worked.

When the medicine is tried with six patients, X is the number of patients for whom the medicine worked.

Answer 7

I believe it would be everything except the first option since X = the number of patients (success or fail)

Answer 8

if that doesn't work then I would only pick the last two

Answer 9

hint: if P(success) * P(success) = 0.36 then what is P(success)?

Answer 10

9?

Answer 11

no wait

Answer 12

what is the square root of 0.36?

Answer 13

0.6

Answer 14

good, that's your answer

Answer 15

hint: what is the probability of landing on A or B?

Answer 16

1/3

Answer 17

in probability "or" implies addition

probability of A + probability of B = ?

Answer 18

2/3?

Answer 19

good, and if we square that (for X = 2) we get?

Answer 20

B?

Answer 21

what is (2/3)*(2/3) ?

Answer 22

1

Answer 23

what is 2*2?

Answer 24

4

Answer 25

good, what is 3*3?

Answer 26

9

Answer 27

good, so (2/3)*(2/3) = 4/9

so if X = 2 gives us a probability of 4/9 that means only option #1 (top left) works

Answer 28

The probability that traffic lights on a certain road will be green is 0.6. When a driver on that road approaches two traffic lights in a row, X is the number of traffic lights that are green.

What is P(X=1)?



Enter your answer, as a decimal,

Answer 29

if 0.6 is the probability of green, what is the probability of NOT green?

Answer 30

0.4?

Answer 31

good

so we have two possibilities

green * not green
not green* green

so that gives us (0.6)(0.4) + (0.4)(0.6) = ?

Answer 32

0.48

Answer 33

good that should be your answer

Answer 34

thanks!