Question

find the missing probability?
x 1 2 3 4
P(X) 0.30 0.40 0.15 ?

Answer 1

Hint: in any valid probability distribution, all the probabilities must add to 1

Answer 2

soo that means???

Answer 3

0.3 + 0.4 + 0.15 + x = 1

solve for x

Answer 4

idk what x is lol thats why i put it on here.
i cant miss this one or i fail. sorry im not good with thid

Answer 5

x is unknown and you don't know it until you solve for it

Answer 6

0.3 + 0.4 + 0.15 + x = 1

0.85 + x = 1

x = 1 - 0.85

x = ???

Answer 7

if we knew what x was, then there would be no need to ask the original question

Answer 8

do i just minus 1 from 0.85?

Answer 9

yes

Answer 10

1 - 0.85 = ???

Answer 11

i got 0.15

Answer 12

same here

Answer 13

so is that right?

Answer 14

yes, that's the missing probability

Answer 15

thank you

Answer 16

basically you have 4 different possibilities

possibility A has a 30% chance
possibility B has a 40% chance
possibility C has a 15% chance
possibility D has a 15% chance (you just found this one)

They add to 100% and there are no other possibilities

Answer 17

and they must add to 100% if these are the only 4 possibilities