Question

On dec 18th there is a 75% chance that santa will come to the mall that day and a 55% chance that your best fri d will be at the mall. There is a 40% chance that your best friend and santa will be at the mall. What is the probability that santa will come to the mall or your best friend will be there?
A. 90%
B.85%
C.70%
D.75%

Answer 1

The probability that santa will come to the mall or your best friend will be there is 90% ⇒ A

Step-by-step explanation:

The addition rules of probability are:

• P(A or B) = P(A) + P(B) ⇒ mutually exclusive (events cannot happen  at the same time)
• P(A or B) = P(A) + P(B) - P(A and B) ⇒ non-mutually exclusive (if they  have at least one outcome in common)

∵ There is a 75% chance that santa will come to the mall that day

∴ P(santa) = 75% = 75 ÷ 100 = 0.75

∵ There is a 55% chance that your best friend will be at the mall

∴ P(friend) = 55% = 55 ÷ 100 = 0.55

∵ There is a 40% chance that your best friend and santa

    will be at the mall

∴ P(friend and santa) = 40% = 40 ÷ 100 = 0.4

To find the probability that santa will come to the mall or your best friend will be there use the non-mutually exclusive addition rule

∵ P(friend or santa) = P(friend) + P(santa) - P(friend and santa)

∴ P(friend or santa) = 0.55 + 0.75 - 0.4

∴ P(friend or santa) = 0.9

- Change it to percentage by multiplying it by 100%

∴ P(friend or santa) = 0.9 × 100% = 90%

The probability that santa will come to the mall or your best friend will be there is 90%

Learn more:

You can learn more about the probability in brainly.com/question/9178881

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