ATAR Notes: Forum

VCE Stuff => VCE Mathematics => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE General & Further Mathematics => Topic started by: marbs on July 23, 2008, 07:55:28 pm

Title: two questions need help clarifying
Post by: marbs on July 23, 2008, 07:55:28 pm

1. Calculate the standard deviation

Mean = 38.4
Z score = 0.95
X value = 42.2

I got standard deviation of 4... Is that right?

2. A 68, 95, 99.7% question

Alright, so we had a list of measurements for animals at a zoo. We had to choose a particular zoo. There were 45 animals.

We had to calculate its 68% I got something (forgotten)

We then had to calculate the values in there. I counted all values between 1 standard deviation point either way.

I counted 29.     29/45 = 64%

The question - Determine whether this equation would fit in a normal distribution?  :idiot2:

I said it would because it was close enough to 68%....? Is this right... what would you have said.

Thanks.

Title: Re: two questions need help clarifying
Post by: marbs on July 23, 2008, 09:15:18 pm

anyone... I need it for tomorrow....

Title: Re: two questions need help clarifying
Post by: Mao on July 23, 2008, 10:13:35 pm

1) 4 is correct

2) cannot understand you. :P

Title: Re: two questions need help clarifying
Post by: marbs on July 23, 2008, 10:23:49 pm

haha thanks. I know as I was type it was hard to understand.

I'l try one last time...

• They asked to calculate the amount of x values in the 68% region
  I calculated that 64% of the values were in there (might have made an error)
  They asked 'From this knowledge would it be considered a normal curve'
  I said yes

I'm remembering from the top of my head so it might still be confusing sorry

Title: Re: two questions need help clarifying
Post by: Mao on July 23, 2008, 10:26:51 pm

quite clearly this is related to a SAC

but I really aren't helping you at all

your reasoning does appear correct, but that's only from the info given. I'm afraid I cannot comment any further :P

Title: Re: two questions need help clarifying
Post by: bigtick on July 23, 2008, 10:33:12 pm

You need to check +/- 2 sd and 3 sd for 95% and 99.7%. The last one is considered as 100%.

Title: Re: two questions need help clarifying
Post by: marbs on July 23, 2008, 10:41:19 pm

cheers its all good now.

I found it on wiki lol, an unlikely source I would have thought