Question

Let an integer be chosen at random from the integers 1 to 30 inclusive. Find the probability that the integer chosen is divisible by 4 or is greater than 25 and less than 30.



1/3

11/30

2/5

Answer 1

@yordicecream

Answer 2

P(A or B)=P(A)+P(B)-P(A and B)

Answer 3

1/3?

Answer 4

well how many multiples of 4 are there between 1 and 30?

Answer 5

7

Answer 6

ok and how many integers are between 25 and 30

Answer 7

4

Answer 8

ok and how many of those numbers that were a multiple of 40 that is also between 25 and 30

Answer 9

multiple of 30*

Answer 10

\[P(A \text{ or } B)=P(A)+P(B)-P(A \text{ and } B)=\frac{7}{30}+\frac{4}{30}-\frac{?}{30}\]

Answer 11

we just need that last number there

Answer 12

4(1),4(2),4(3),4(4),4(5),4(6),4(7)
lol I said multiple of 30

Answer 13

how many of those numbers are between 25 an 30

Answer 14

30?

Answer 15

4(1)=4
4(2)=8
4(3)=12
4(4)=16
4(7)=28

Answer 16

hmmm the only number i see between 25 and 30 is...

Answer 17

28

Answer 18

that is 1 number

Answer 19

\[P(A \text{ or } B)=P(A)+P(B)-P(A \text{ and } B)=\frac{7}{30}+\frac{4}{30}-\frac{1}{30}\]

Answer 20

10/30

Answer 21

but theres no 10/30 in the options... so i think its 1/3 since its equivalent to 10/30

Answer 22

I think you know that 10/30 reduces to 1/3 in your deepest of hearts

Answer 23

so im right?

Answer 24

divide top and bottom by 10
\[\frac{10}{30} \frac{\frac{1}{10}}{\frac{1}{10}}=\frac{1}{3}\]

Answer 25

thnx