Question

USE FOR MASTERY Number of attempts allowed: 1 Write two rational numbers a/b and c/d, where a, b, c, and d are the digits 2, 3, 4, or 5, such that no digit can be used more than once and that the two rational numbers are the greatest distance apart on the number line. Explain how you got this answer.

Answer 1

We want to craft:

a/b and c/d

where a, b, c and d can be 2, 3, 4 and 5.

Such that the distance in the number line between these two numbers is maximized.

Then we want one number to be really small, and the other to be really large.

Remember two things:

for numbers like a/b.

if a is smaller than b, then a/b is smaller than 1.

Now, if a is larger than b, then a/b is larger than 1.

And two things,

1/10 = 0.1

10/1 = 10

So when the numerator is larger, the distance displaced in the number line is larger.

Then we want to have:

a number where the numerator is the largest option and the denominator is the smallest option:

a/b = 5/2

And the two remaining options in such way that the numerator is smaller than the denominator:

c/d = 3/4.

The distance between these two numbers is:

D = 5/2 - 3/4 = 10/4 - 3/4 = 7/4.