# Tutor profile: Haotian C.

## Questions

### Subject: Basic Math

What does $$1+6 \div 2(4-1)$$ equal?

If you said 2, I'm sorry that is incorrect. The answer is actually 10. Let's take a look at PEMDAS (also remember that multiplication and division hold the same priority so always do it in order from left to right). We do the parenthesis first so $$4-1=3$$ so the equation becomes $$1+6 \div 2(3)$$. Now we do multiplication and division, but here's the gotcha, we have to divide 6 by 2 first before we multiply by 3 because we are going left to right, so the equation become $$1+3(3)$$ then $$1+9$$. Finally we add 1 and 9 together to get 10.

### Subject: ACT

What is the score you should be aiming for on the ACT?

Well the answer depends on you. If you can't get a perfect score that's fine, neither can the other 99.9% of the people taking the test. Your goal should be the best that you can do then push yourself just a little more :).

### Subject: Physics

If you want your coffee to stay warm for longer, should you add the creamer immediately or wait?

Due to the Stefan-Boltzmann law ($$ I = \sigma( T^4 -S^4$$) where I = the Intensity of the radiating heat in $$joules/m^2 s, $$, $$\sigma$$ = $$5.67^{-8} Watt/m^2 K^4$$ the Stefan-Boltzmann constant, T = the temperature of the coffee, and S = the temperature of the surrounding), you should at the creamer immediately. Although the addition of creamer will immediately lower the temperature of the coffee, that lowering of temperature the difference between the coffee and the surrounding will be smaller and thus the intensity of the radiating heat will be lower.

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