alice-teacher question regarding bits and bytes!

[Melia, James E.]

What books are you using?
What books are currently recommended for (1) Alice and (2) Java with Alice?
Jim Melia, Lansdowne High School, Baltimore County Schools

From: alice-teachers-bounces+jmelia=bcps.org at lists.andrew.cmu.edu [mailto:alice-teachers-bounces+jmelia=bcps.org at lists.andrew.cmu.edu] On Behalf Of Sandy Graham
Sent: Wednesday, March 12, 2014 9:11 PM
To: 'Alice educators'
Subject: Re: alice-teacher question regarding bits and bytes!

I have two students who have completed the entire Alice book. They did every definition, question and programming assignment in the book! We have moved onto a java book to prep them for the AP exam. Chapter 1 of that book has the following question:
“If a picture was made up of 64 possible colors, how many bits would be needed to store each pixel of the picture?”
I thought RGB values would be required so was trying to figure out an answer from that (though the book doesn’t give much information on how to do that exactly), but the answer key says the answer is 6. I can see that 2^6 = 64 and assume that’s where the 6 came from, but why is that the answer? How does 6 bits yield 64 possible colors? Don’t RGB values have to be considered?

Then the next question asks, “How many bits are there in 12 KB?”
So 12 * 2^10 = 12,288, right? I’m pretty con fident of my answer, but I wanted to double check with a reliable source as the answer key says 98, 304 is the correct answer. The key is wrong, right?

Thanks! I didn’t know where else I could get a reliable answer to this!
Your sister in Christ,

Sandy Graham

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