VCAA Questions

[Hye]

2002 exam 2. Q2 (b)
One technique for telling the difference between the two species is by measuring the length of their antennas. For Fhaisi butterflies, antenna lengths are normally distributed with a mean of 20 mm and a standard deviation of 2 mm.
b.   Find the probability, correct to three decimal places, that a randomly selected Fhaisi butterfly antenna is shorter than 16 mm.

answer is 0.023. i got 0.025 from the 68-95-99.7%

[Linkage1992]

Use the calculator, and you'll get their answer.
This is exam 2, you can't rely on inaccurate methods.

[superflya]

yea normcdf(,16,20,2) = 0.023, ohh wait u had to use the normal distribution tables bak then -.-

[Hye]

yea normcdf(,16,20,2) = 0.023, ohh wait u had to use the normal distribution tables bak then -.-

so you would get 2 marks for writing that and the answer?

[JinXi]

wouldn't u have to write X~N(20,4)

Pr(X<16) = 0.023?

[superflya]

wouldn't u have to write X~N(20,4)

Pr(X<16) = 0.023?

yea u need to include this to get the method mark, what i wrote was the calculator input.

[andy456]

yea normcdf(,16,20,2) = 0.023, ohh wait u had to use the normal distribution tables bak then -.-

so you would get 2 marks for writing that and the answer?

I'm pretty sure I've been told or read that calc syntax isnt correct, but i may be wrong

[Hye]

vcaa 2003 q 2d(i) its referring to a diagram on previous page

thanks

[gossamer]

yea normcdf(,16,20,2) = 0.023, ohh wait u had to use the normal distribution tables bak then -.-

so you would get 2 marks for writing that and the answer?

I'm pretty sure I've been told or read that calc syntax isnt correct, but i may be wrong

Yup, I was doing VCAA exams this morning, and practically every second question in the Assessor's Report says to "avoid calculator syntax". Also, in the comments, they said they expect maths notation.... so use it.
Sucks, coz I tend to always write calc syntax, my teacher never said not to. Gah.