Sorry mods, could you delete please, problem solved! Thanks
S1 question help - solved Watch
- Thread Starter
Last edited by iced_dragon_agility; 22-12-2010 at 20:14. Reason: please delete
- 22-12-2010 20:11
- 22-12-2010 20:26
This is how to tackle the question:
1.78 m once in 5 attempts
This means that it was 20% of the time. From a normal distribution table this is 1 - 20% = -80% which = - 0.8416.
The correct formulae is Z x standard deviation + mean = X
This means -0.8416 x standard deviation + mean = 1.78
That is the first part done. Next part:
1.65m 7 in 10 attemps.
This means that it was 70% of the time. From a normal distribution table that is 0.52440.
Substitute this into the correct formulae again.
This means 0.52440 x standard deviation + mean = 1.65.
Now you use simultanious equations to work them out. You cancel them, the means cancel out, you can work that out later.
You now get -1.366x standard deviation = 0.13.
This means standard deviation is 0.13 divided by -1.366.
The answer is therefore 0.095.Last edited by Heritage Oil; 22-12-2010 at 20:36.