Question

find the probability that a number chosen at random between 200 and 800 inclusive will be a multiple of 9

Answer 1

so like a first step what is a number multiple of 9 ? what mean this ?
- between 200 and 800 how many the same numbers are there ?

Answer 2

first find the least number >=200
to do so divide by 9
9| 200

Answer 3

it is an A.P. sequence.
d=9
a1=207
an=792
use the formula to find n.
an=a1+(n-1)d
this gives number of favorable events.
total number of events=800-200+1=601 (as both 200 and 800 are calculated.)
then finally find the probability.