# Tutor profile: Xinyuan (Christine) Z.

## Questions

### Subject: Basic Math

48 / 2(9+3)=?

The question seems simple but is actually not. The answer is 288, but not 1. It's about order of operations in math.

### Subject: Mandarin

__ 他比我大一岁， __ 我的辈分比他大。 a. 不但…而且 b. 虽然…可是 c. 因为…所以 d. 既然…那就

The answer should be B. "他比我大一岁" means "he is one year older than me". "我的辈分比他大" means "my position in the family hierarchy is higher than him." There is a transition, so the answer should be, which is "Although...but...".

### Subject: Calculus

A jet accelerates along the runway and takes off. It consumes fuel at a rate of f (t) = t2 /￼(t +1)^3kL per minute. How much fuel does the jet consume in the first 3 minutes?

By the Evaluation Theorem, the amount consumed from t=0 to t=3 minutes is [integration 0 to 3, t^2/(t+1)^3 dt]. We make the substitution u = t + 1 to make the denominator nicer, then we expand. [integration 0 to 3, t^2/(t+1)^3 dt] = ln(4)-32/32=0.355 KL

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