z-scores (1 Viewer)

[mike524]

I am having trouble with this, can someone please help
thanks
Mike

 

[grk_styl]

it goes by the formula

z score = (score - mean) divided by the standard deviation. So if you're asked this question:

Question:"Mina received the mark 75 in her english exam. In the class the mean was 62 and the standard deviation was 8. Find her z score and what this means."

Answer:

z = (75 - 62) / 8
= 1.625
:. z = 1.6 (1 dp)

This means that Mina's score is 1.6 standard deviations above the mean.


It's basically quite a good topic if u just follow the formula. They can also GIVE u the z-score and ask u to find the Standard Deviation, so all u do is work back from the formula.

Hope that helps.

 

[Misturi]

Also if its a minus z-score - it is below the mean.

 

[Misturi]

the formula for z scores is on the formula sheet too

Gotta love those formula sheets...

except they don't give you the formula for area of a trapezium...

 

[Misturi]

Do they give you the formula for circumfrence for a circle?

 

[grk_styl]

Also if its a minus z-score - it is below the mean.

yes, so if u got a z-score of -2 that would mean that you're 2 standard deviations below the mean, ie. NOT a good mark.

 

[lilmzqt]

Do they give you the formula for circumfrence for a circle?

i dun think they do coz i think we expected to no dat........only new formulas we learn in yr 11 & 12 are given to us.......which sux!

 

[Happeninchick]

No - you are meant to know the circumference of a circle formula. Bit annoying that they don't give it you. Same with the area of a trapezium. Be prepared to get a question based on that. The formula is not given on the sheet.

 

[grk_styl]

I've completed heaps of past papers, and majority of the time there has been a question making u use the Trap. Formula, so yes make sure you know it

I use to have big problems trying to remember formulas (even thru junior years), but I'm good at it now and I put it down to practice. Keep doing heaps of questions which require you to use formulas. Try to use a formula without checking it up. If you forget it, find it out then write it out a few times and see if you remember it the next day. Don't just wake up and say, "ok what's the formula for a circle?". Open your text book and find a question which involves the formula - it'll help you learn them better

it works, i promise!

 

[inasero]

the 'z-score' is basically how many standard deviations from a mean a particular statistic is

 

[Misturi]

yes, so if u got a z-score of -2 that would mean that you're 2 standard deviations below the mean, ie. NOT a good mark.

Yeap, it took me a while to understand that and wondered why it didn't go below -3 or above 3!

 

[Misturi]

No - you are meant to know the circumference of a circle formula. Bit annoying that they don't give it you. Same with the area of a trapezium. Be prepared to get a question based on that. The formula is not given on the sheet.

True, especially when finding out the area of a field based on surveyors numbers. They mostly slip a trapezium in there. You could work it out by making it into a square/rectangle with two triangles but that would take too long.

Tha formula isn't that hard anyways

h/2 (a + b) where a and b are the two parralell sides and h is the height.

 

[timrie6]

Does anyone know their z-score for their trial mark?