# Are the SDMB members smarter than an 8th Grader? **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [August 14, 2013, 10:38am UTC](https://boards.straightdope.com/t/are-the-sdmb-members-smarter-than-an-8th-grader/666203 "2013-08-14T10:38:52Z")\ **Posts on this page:** 6\ **Page:** 2
**Author:** ![OldGuy](https://avatars.discourse-cdn.com/v4/letter/o/3bc359/32.png) [@OldGuy](https://boards.straightdope.com/u/OldGuy)\ **Post date:** [August 15, 2013, 1:07am UTC](https://boards.straightdope.com/t/are-the-sdmb-members-smarter-than-an-8th-grader/666203/21 "2013-08-15T01:07:39Z")
> [@Doctor\_Jackson](#): > > Find the amount of $50.30 for 3 years, 3 mo. and 3 days, at 8 percent Having read some old arithmetic texts from around this era, I would make a sizable bet you are to assume that 3 mos is exactly 1/3 of a year and 3 days is exactly 1/10 of a month and therefore 1/120 of a year so you have interest for 3 41/120 years. Furthermore you are to assume simple interest. So total interest is .08\*(3 41/120)\* principle. However, I’m not sure of the wording on the problem that 50.30 is the principle and you’re to find interest or if it’s the interest and you’re to find principle. ---
**Author:** ![pulykamell](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pulykamell/32/3166_2.png) [@pulykamell](https://boards.straightdope.com/u/pulykamell)\ **Post date:** [August 15, 2013, 1:32am UTC](https://boards.straightdope.com/t/are-the-sdmb-members-smarter-than-an-8th-grader/666203/22 "2013-08-15T01:32:58Z")
> [@OldGuy](#): > > Having read some old arithmetic texts from around this era, I would make a sizable bet you are to assume that 3 mos is exactly 1/3 of a year Really? Not 1/4 of a year? Why would they want you to assume 3 mos is 1/3? That makes little sense to me. ---
**Author:** ![aceplace57](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aceplace57/32/3500_2.png) [@aceplace57](https://boards.straightdope.com/u/aceplace57)\ **Post date:** [August 15, 2013, 3:57am UTC](https://boards.straightdope.com/t/are-the-sdmb-members-smarter-than-an-8th-grader/666203/23 "2013-08-15T03:57:41Z")
That had to be a typo. Fiscal Quarters are standard throughout business. I vaguely recall from a business math class that there used to be quite a few defaults used. Back when interest and other things were hand calculated they just weren’t that anal about it. A month was 30 days. 4 months made a quarter of a year and so forth. I can’t recall that stuff now. That was a class 20 years ago and I never really used that math again. I do remember spending several weeks on loan calculations. Present value, future value etc. All of it we did by hand back then except for the basic math (used a plain calculator, Not a fancy business calculator). ---
**Author:** ![pulykamell](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pulykamell/32/3166_2.png) [@pulykamell](https://boards.straightdope.com/u/pulykamell)\ **Post date:** [August 15, 2013, 4:25am UTC](https://boards.straightdope.com/t/are-the-sdmb-members-smarter-than-an-8th-grader/666203/24 "2013-08-15T04:25:17Z")
> [@aceplace57](#): > > 4 months made a quarter of a year and so forth. You mean 3 months. 3 months = 1/4 year. 4 months = 1/3 year. ---
**Author:** ![aceplace57](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aceplace57/32/3500_2.png) [@aceplace57](https://boards.straightdope.com/u/aceplace57)\ **Post date:** [August 15, 2013, 4:44am UTC](https://boards.straightdope.com/t/are-the-sdmb-members-smarter-than-an-8th-grader/666203/25 "2013-08-15T04:44:01Z")
😛 Whoops. right. My boss would be irked if I did the quarterly database reports and backups every four months. It’s every three months. ---
**Author:** ![OldGuy](https://avatars.discourse-cdn.com/v4/letter/o/3bc359/32.png) [@OldGuy](https://boards.straightdope.com/u/OldGuy)\ **Post date:** [August 15, 2013, 11:33pm UTC](https://boards.straightdope.com/t/are-the-sdmb-members-smarter-than-an-8th-grader/666203/26 "2013-08-15T23:33:06Z")
Sorry yes. 3 months = exactly 1/4 year. Interest rate calculations then (and sometimes still now) assume that every month is exactly 30 days (even February). This is known as the 30/260 convention. See [Day count convention - Wikipedia](http://en.wikipedia.org/wiki/Day_count_convention) for more information than you could probably want. [Previous page](https://boards.straightdope.com/t/are-the-sdmb-members-smarter-than-an-8th-grader/666203.md?page=1)