Question

what is the difference in length?? (i don't understand)

Answer 1

They could have said diameter instead of length.
The difference in size is 1¼ - ⅜.

Convert the mixed number to a improper fraction:
1¼ = 5/4

Give the fractions a common denominator. The least common denominator is 8
5/4 = 10/8


1¼ - ⅜ = 10/8 - ⅜ = (10-3)/8 = ⅞”