One day, River writes down the numbers $1,$ $2,$ $\dots,$ $999.$ River chooses one of the digits written down at random. What is the probability that River chooses a $7$?

100/963

Step-by-step explanation:

The number 1,2,3,...,999 is written down.

First, we determine the total number of digits written down

Total Number of digits=9+2(90)+3(900) =2889

Number of Digit 7 between 1 and 999

Therefore, the number 7 will be found a total of 300 times between 1 and 999.

Therefore, the probability of selecting a "7"  =  300/2889  

= 100/963

step-by-step explanation:

it's 15

ok then what happened.