# Tutor profile: Changeon Y.

## Questions

### Subject: Basic Math

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### Subject: Statistics

There are 3 white balls and 7 black balls in the jar. When randomly choosing, (1) what is the probability that you choose white ball? (2) what about black balls? (3) when you choose 3 balls and what is the probability that you choose 1 white ball and 2 black ball?

1. Probability of choosing white ball = P (white ball) = 3/10 2. Probability of choosing black ball = P (black ball) = 7/10 3. [C(3,1) * C(7,2)] / C(10,3) = 7/80

### Subject: Algebra

Solve the equations 1. 6/(x+5)-3/(x-3)=6/(x^2+2x-15) 2. 4/(2x-3) + x/(x+1) = -8x/(2x^2-x-3)

1. (1) 6/(x+5)-3/(x-3)=6/(x^2+2x-15) (2) 6(x-3)/(x^2+2x-15)-3(x+5)/(x^2+2x-15)=6/(x^2+2x-15) (3) (3x-33)/(x^2+2x-15)=6/(x^2+2x-15) (4) 3x-33=6 (x≠3 & x≠5 as no numerator can't be 0) (5) x=13 2. (1) 4/(2x-3) + x/(x+1) = -8x/(2x^2-x-3) (2) (4(x+1))/(2x^2-x-3)-(x(2x-3))/(2x^2-x-3)=(-8x)/(2x^2-x-3) (3) (2x^2+x+4)/(2x^2-x-3)=(-8x)/(2x^2-x-3) (4) 2x^2+x+4=-8x (5) 2x^2+9x+4=0 (6) (2x+1)(x+4)=0 (7) x=-1/2 or x=-4

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