Destroyer Problem#34 GC

[jdpaul14]

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Hey Guys,

I had a quick ? about ksp. On #34 of destroyer why are we supposed to neglect x in (x + 0.025)?...it says its because the ksp is very small: 1.6 X 10^-14

What is the Ksp were higher?? If it were higher would we keep the equation as (x + 0.025)

Hope this questions wasn't too confusing....

 

[nze82]

Hey Guys,

I had a quick ? about ksp. On #34 of destroyer why are we supposed to neglect x in (x + 0.025)?...it says its because the ksp is very small: 1.6 X 10^-14

What is the Ksp were higher?? If it were higher would we keep the equation as (x + 0.025)

Hope this questions wasn't too confusing....

I'm not sure, what the question is. But you're not ignoring (x+0.025) altogether. What you're ignoring is x, which is much smaller compared to 0.025. In other words:

(x+0.025) ~ 0.025

Try solving for x, you'll see that it'll end up being something in the order of 10^-7 (or something in that range). 10^-7 = 0.0000001. Obviously this is not very different from 0. So:

0.0000001 + 0.025 = 0.0250001 ~ 0.025

This is why you can ignore x in the above calculation. Hope this makes sense.

 

[joonkimdds]

I spent tons of time to remember all GC calculations from destroyer and I am actually really good at these now.

But I heard that actual DAT doesn't have it XD.

 

[nze82]

I spent tons of time to remember all GC calculations from destroyer and I am actually really good at these now.

But I heard that actual DAT doesn't have it XD.

Remember calculations? Why? There's no point to memorize calculations.
About whether or not the actual DAT involves lots of calculations, I must say every test is different. My test was 80% calculations, which I didn't mind at all. But I've heard people who only had 7-8 questions involving calculations. So, it really depends on what kind of test you get.

 

[jdpaul14]

Thanks a lot guys! That explanation really helped!! 🙂