Question

What are the odds of a 1/5 roll not displaying a 1 after 30 rolls?

Answer 1

like a 5 sided dice huh?

Answer 2

sure

Answer 3

the odds of not getting a 1 on the first try:
\[\Large \frac 45\]

the odds of not getting a 1 on the 2nd try:
\[\Large \frac 45\times\frac 45\]

Answer 4

\[\left(\frac{4}{5}\right)^{30}=\frac{1152921504606846976}{931322574615478515625}=0.001238 \]

Answer 5

so its (4/5)^n (let n be the number of rolls?)

Answer 6

ok forgive me, but how do i calculate out ^n ... i mean physically how is that calculated

Answer 7

(4^30)/ (5^30) ?

Answer 8

sure

Answer 9

Yes

Answer 10

Ok ty very much for the help guys

Answer 11

@robtobey's answer was calculated using the Mathematica program which provides unlimited precision integer arithmetic.

Answer 12

@PaxPolaris thanks @robtobey for this information

Answer 13

You are welcome.