Create a spreadsheet to represent something in your life: grades, how much you spend from month to month, how much you weigh from week to week, something related to your HW2 research essay, whatever. (The numbers don't have to be real!) Include at least one formula and at least one chart.
Anne and Bob just got married, and they're now sharing living expenses. Each has a bank account, and they also have a joint bank account. Some expenses are his (e.g. his donations to political organizations that she's not interested in), some are hers (e.g. her favorite computer game), and some (like the rent and the groceries) they've agreed to share in proportion to their incomes (he makes $40,000 and she makes $60,000, so she pays 60% of the shared expenses). This would all be easy if he could pay for his expenses from his account, she could pay for hers from her account, and they could pay for the shared expenses from the joint account... but sometimes he wants to buy something and has forgotten his own checkbook and credit cards, so they use hers or the joint checkbook, and vice versa.
Create a spreadsheet to compute who owes how much to whom at the end of the month. It should have clearly-labelled cells to enter
For example, suppose last month Anne paid $50 for Bob's expenses and $200 for joint expenses, Bob paid $200 for joint expenses, and the joint account paid $600 for joint expenses. You would enter these four numbers into the appropriate cells, and the spreadsheet should then calculate as follows:
Anne has paid a total of $250, Bob has paid a total of $200, and the joint account has paid a total of $600. Anne had no expenses of her own, Bob had $50 in expenses, and there were $1000 in joint expenses (the $50 and the $1000 should appear in the pie chart). Dividing the joint expenses 60/40, Anne should have paid $600 of them and Bob should have paid $400. Anne has already paid $250, so she owes somebody $350. Bob has already paid $200, leaving $200, but he's also liable for the $50 Anne spent on his behalf, so he owes somebody $250. So Anne transfers $350 into the joint account, Bob transfers $250 into the joint account, and the joint account is back up to strength so it can pay next month's bills.
Once you've written your spreadsheet, test it on these numbers and make sure you get the same answers; then test it again on different numbers that you've made up, and make sure the answers are still correct. I'll test it by plugging in different numbers; if your answers don't match mine, you'll lose points.
Note: it's possible that at the end of the month, the joint account owes Anne or Bob money rather than the other way around. The obvious way to write the spreadsheet will have Anne or Bob transferring a negative amount of money into the joint account. For extra credit, use four "answer" cells rather than two: "Anne owes joint account", "Bob owes joint account", "Joint account owes Anne", and "Joint account owes Bob", and write formulae so that the cells with negative numbers show up as 0.00 -- or, even better, as empty.