the weight of a packet

[monokekie]

could anyone please solve this ess qstn, thanks.

The weight of a packet of biscuits is known to be normally distributed with a mean of 1 kg, if a packet is more than 0.05 kg underweight, it is unacceptable, If it is found that 3 % of packets are unacceptable, then the standard deviation of the weight is?

[zzdfa]

if i told you something was 5 standard deviations above the mean, would you know how to find out what % of the population is above that?

this is just the reverse, you're given the % (shaded blue area) and you have to find how many standard deviations from the mean it is (use calculator)

after you do that, you can solve for the standard deviation:    

(s is the number of standard deviations away from the mean, if you think about it! and the mean is given, and Z is given as well)

s

[monokekie]

OMG i got it! thanks soooo much zzdfa! nice drawing btw