Hello,
One method of finding a value in between two other numbers is taking the average, it will always be between the numbers. To find the average of two numbers, add the numbers and divide it by how many numbers there are.
In this case, we have:
(0.3) + (0.5) /2 = 0.8 / 2 = 0.4
So, 0.4 is one length that is within the given span.
Another example is 0.45, which is also between 0.3 and 0.5.
0.4 represented as a fraction is 4/10. However, this can be simplified (notice 4 and 10 are both divisible by 2). To simplify this fraction, divide the numerator and denominator of the fraction by 2 to get (4/2) / (10/2) = 2/5.
0.45 represented as a fraction is 45/100. This fraction can also be simplified (notice 45 and 100 are both divisible by 5). To simplify this fraction, divide the numerator and denominator of the fraction by 5 to get (45/5) / (100/5) = 9/20.
Two lengths that are within the span are 2/5 inches and 9/20 inches, both of which are in simplest form.
Hope this helps!