## Wednesday, May 12, 2010

Yesterday's blog post was about teaching time in math class. Today I want to share a practical application for a grown-up person using elementary math to solve a time problem.

We have to create a slideshow for a social event. Here are the facts:
• We have collected roughly 100 photos. Well, 104 to be exact.
• We have a piece of music we like that runs for 20 minutes and 48 seconds.
• We have experimented with timing and feel that 15 seconds is adequate for each slide.
Here are the questions:

Q1. If I set the slide show to go exactly 15 seconds per slide, will my music be long enough?

A1. 104 x 15 = 1560 seconds. 1560 ÷ 60 = 26 minutes. The music is NOT long enough.

Q2. I can allow the software do the work of evenly dividing the slides across the timing of the music. What will the timing be per slide?

A2. 20 minutes 48 seconds = 1248 seconds ÷ 104 = 12 seconds per slide.

Q3. We need to show the program 5 times. Will the laptop computer batteries last long enough or will I need the power cord? I can put the computer to sleep in-between the shows. I estimate about 30 minutes total running time for each show, between start and sleep.
A3.  In magazine reviews, the computer seems to have "about 4 hours" of battery life.
4 x 60 = 240 minutes. 5 x 30 = 150 minutes. 240 - 150 = 90 minutes reserve power.
I should be able to run the slide show on the battery.

Extra Credit Question: How many different slides are shown in the first photo at the top of this post?