12A Questions

[calcguy1350]

Forum's been dead...

On 12A-61, I might be doing it wrong, don't know, but what do you guys get...I keep getting 1.04
Maybe this has already been asked, so i'm sorry, bad memory. :)

12A-36 The mass of the earth is 5.972E24 kg. What is the percent error in calculating the mass based on an average density of 5.163 g/cm^3? Answer: 1.9(2SD)
I can get the right answer, I just don't know how to get the 2 significant figures so I need a detailed explanation.

Just as a side note, I like how the overflows aren't just straight out numbers this year like #37.

Thanks in advance!

[calcguy1350]

Shawn? Anyone?

[007math]

For #61 I am getting 1.04 as well so maybe answer key error?

[calcguy1350]

Yes, probably an answer key error.

Never mind, I got the other one.

[88bobcat]

[rcoker7]

You're doing it right. The density is actually supposed to be 5.613 g/cm^3. Just a typo in the op.

[88bobcat]

[calcguy]

You're right, you use the unrounded numbers all the way to the end, then do the SD analysis. The equatorial radius of Earth is 3963 mi. The polar radius is 3950 mi. Dr. Bourell uses the volumetric mean radius which is 3960 mi to 3 significant digits. It's in his Calculator Applications Contest Manual along with all the conversion factors you need to use on the calculator test. Your calculation gives the correct answer if you use 3960 mi for radius of Earth.

[88bobcat]