Question

Sandy is trying to reconstruct her spending pattern from July. She knows that she had $277 in her account on July 1, but after that, her receipts and balance statements are all scrambled. Here are Sandy’s records:

Date
Transaction Type
Amount ($)
7/26
Purchase
86
7/25
Deposit
76
7/4
Purchase
137
7/6
Deposit
90
7/10
Purchase
131
7/9
Purchase
145
7/15
Deposit
152
7/19
Purchase
137

Assuming that this is a complete, if scrambled, record of Sandy’s July spending and that any overdraft fees incurred do not affect the running total, how many times did Sandy overdraw her account in July?
a.
Sandy never overdrew her account.
b.
Sandy only overdrew her account once.
c.
Sandy overdrew her account twice.
d.
Sandy overdrew her account more than twice.

Answer 1

Put the transactions in date order and keep a running balance from the July 1 balance of $277:

- 7/4 Purchase 137 → 277 − 137 = 140
- 7/6 Deposit 90 → 140 + 90 = 230
- 7/9 Purchase 145 → 230 − 145 = 85
- 7/10 Purchase 131 → 85 − 131 = −46 (overdraft #1)
- 7/15 Deposit 152 → −46 + 152 = 106
- 7/19 Purchase 137 → 106 − 137 = −31 (overdraft #2)
- 7/25 Deposit 76 → −31 + 76 = 45
- 7/26 Purchase 86 → 45 − 86 = −41 (overdraft #3)

Sandy overdraw her account three times, so answer: d (more than twice).