vol 1 3pm #15.1 and 18.4

In vol 1 3pm questions 15.1 and 18.4 both had to do with the number of futures to hedge a bond position. In #15.1 was hedging an 80 bp change in rates. Whether you apply the 80 bp or not it doesn’t matter because both the numerator and denominator would get adjusted so you get the same answer either applying the 80bp or not applying it. My question is in #18.4 you had to hedge a 50bp change in rates. The answer key only applied the 50bp change to the numerator and not the denominator. Aren’t both questions relatively the same? Why not apply the bp change the same way in both questions? Or am I missing something?

Forget it. Just checked the errata and they fixed the answer to 472 contracts for #18.4.