a)I do not understand this one, I just understand that as normal distribution.Originally Posted by Kiwigirl
You need to find .
You need to find how many standard deviations over you moved. Since the mean is 84 and standard deviation is 5 how many standard deviations to you move up to get to 90? Notice that 1 standard deviation up gives 84+5=89 which is too little, while 2 standard deviation gives 84+2x5=94 which is too much. Thus, we need to solve,
solving we have, now we need to look up the precentage on distribution tables, which is .3849. Thus, we have,
Also, since normal distribution is symetrrical we have,
Thus, that leaves over,
Thus, since there were 200 we have approximately 11% of it which is 23.