Official Solution:If an integer between 10 and 50, inclusive is chosen at random, what is the probability that the tens digit is greater than the units digit? A. \(\frac{10}{41}\)
B. \(\frac{11}{41}\)
C. \(\frac{14}{41}\)
D. \(\frac{27}{41}\)
E. \(\frac{30}{41}\)
There are total of 41 integers between 10 and 50 inclusive (check the denominators in the options - all are 41).
We can simply list all the numbers which satisfy the condition:
If the tens digit is 1, there is one number: 10;
If the tens digit is 2, there are two numbers: 20, 21;
If the tens digit is 3, there are three numbers: 30, 31, 32;
If the tens digit is 4, there are four numbers: 40, 41, 42, 43;
If the tens digit is 5, there is one number: 50.
So, there are total of \(1+2+3+4+1=11\) such numbers.
The probability \(=\frac{11}{41}\)
Answer: B