Sam writes down the integers 1-999 inclusive. Sam chooses one of the digits written down at random. What is the probability that Sam chooses a 7?
please help me,
There are a total of 900 integers from 1 to 999 inclusive. The digit 7 can appear in the hundreds, tens, or units place. In the hundreds place, there are 100 numbers that have a 7. In the tens place, there are 90 numbers that have a 7. And in the units place, there are 90 numbers that have a 7. So, there are a total of 100 + 90 + 90 = 280 numbers that have a 7.
Therefore, the probability that Sam chooses a 7 is 280 / 900 = 14/45.
First, you have to count all the digits between 1 and 999.
1 to 9 ==9 digits
10 to 99 ==90 x 2 ==180 digits
100 to 999 ==900 x 3 ==2,700 digits
Total =9 + 180 + 2700 ==2,889 digits between 1 and 999
There are: 300 "sevens" between 1 and 999.
Therefore, the probability of picking a "7" is:
300 / 2,889 ==100 / 963
