Question: Jane Chang is making plans for a summer vacation. She will take $1000 with her in the form of traveler's checks. From the newspaper, she finds that if she purchases the checks by May 31, she will not have to pay a service charge. That is, she will obtain $1000 worth of traveler's checks for $1000. But if she waits to buy the checks until just before starting her summer trip, she must pay a 1% service charge. (It will cost her $1010 for $1000 of traveler's checks.) Jane can obtain a 13% interest rate, compounded weekly, on her money. How many weeks after May 31 can she begin her trip and still justify buying the traveler's checks on May 31?