Mistake in VCAA meth exam 2 ANSWERS

[FromBaghdadWithLove]

hey guys think i found a mistake in vcaa 08 exam 2 answers

im doing probability. so question on page 13, question 1c says i need to
"sketch a PDF , and label the local max with its coordinates correct to two decimal places.

Well i did that, and i had a upsidedown parabola, with the local max being (4.31,0.39) intercepts x at 2 and 6


Point is, this answer is different,
1. Their graph looks retarted.
2. Their has three curves?...
3. " Two decimal places", my ti gace me the point as (4.31,0.385) so i two decimal placed it to (4.31,0.39) ..but vcaa has the answer as (4.31, 0.38)



Correct me if im wrong, but if im right, does that mean everyone who did 0.39 got it wrong? and its their fault...?

yea thanks.

[paulsterio]

Their PDF is right, as you have to consider that apart from just the "Parabola" bit (it's actually a cubic) - the PDF will be = 0 at all other values, so that's what they have represented

I actually think that it might be (4.31, 0.384...) which actually rounds to 0.38 not 0.39

I remember doing it and I managed to get 0.38

[_avO]

yeh 0.3849001.. if you plug in x=4.31 in the equation

[FromBaghdadWithLove]

Ok, but my  calculator is showing the point as 0.385? how do u get more decimal places in a TI whilst on the graph?

also but isn't their shape retarted and its three lines?

[paulsterio]

Nah, the three lines is right, I explained it before

Their PDF is right, as you have to consider that apart from just the "Parabola" bit (it's actually a cubic) - the PDF will be = 0 at all other values, so that's what they have represented

I'm not too sure about the TI though, I use a Classpad which gives around 7 DP on the Graph Screen

[abeybaby]

Depends which ti.. If it's the 89, you can't, if it the nspire, go to settings>graph settings>display digits> float 2 or 3 or 4 etc for however many dps you want