1985 AMC 8 Problem 22
Attempt Problem 22 of the 1985 AMC 8 below, then check your answer against the professionally curated solution from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 1985 AMC 8 solutions, or check the answer key.
All problems are used with official legal permission of the Mathematical Association of America (MAA).
22.
Assume every -digit whole number is a possible telephone number except those that begin with or What fraction of telephone numbers begin with and end with
Answer: B
Small hint:
The first digit can be any of through which is choices
Big hint:
Multiply the fraction of telephone numbers that begin with by the fraction that end in
Solution:
The first digit is one of allowed digits ( through ), so of the numbers begin with The last digit is any of digits, so end in
These conditions are independent, so the fraction is
Thus, the correct answer is B .
Problem 22 in other years
- 1986 AMC 8
- 1987 AMC 8
- 1988 AMC 8
- 1989 AMC 8
- 1990 AMC 8
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