Maths Olympiad Prep

Library / /49 of 168

Algebra Difficulty 1.7 Junior Find the answer

What is the median of the numbers in the list 1920,2019,2019,2019,20×1919^{20}, \frac{20}{19}, 20^{19}, 2019, 20 \times 19?

A number or a short expression. Spacing and $ signs are ignored.

Solution

Since 2019\frac{20}{19} is larger than 1 and smaller than 2, and 20×19=38020 \times 19 = 380, then 2019<20×19<2019\frac{20}{19} < 20 \times 19 < 2019. We note that 1920>1020>1000019^{20} > 10^{20} > 10000 and 2019>1019>1000020^{19} > 10^{19} > 10000. This means that both 192019^{20} and 201920^{19} are greater than 2019. In other words, of the five numbers 1920,2019,2019,2019,20×1919^{20}, \frac{20}{19}, 20^{19}, 2019, 20 \times 19, the third largest is 2019. Since the list contains 5 numbers, then its median is the third largest number, which is 2019.

Want a route through all this instead of an archive? The track puts 2,000 problems in a working order, from AMC 10 level to the IMO shortlist.

Source: Omni-MATH, licensed Apache-2.0. Statement and solution reproduced as published; topic and difficulty added by this site.