Question 1092748
The basic formula is z=(x=mean)/std deviation.
a. z=(11.5-8)/1.5 so z=2.33.  Want z > 2.33 From calculator or table, this probability is 0.0099.
b. z is less than .7/1.5 or 0.47.  This is a probability of 0.3192.
c.  z is -3/1.5 or z is less than -2, with probability of 0.0228
d. z is greater than -3.1/1.5=z is greater than -2.07 or probability 0.9808
e. this is a z between -1.8/1.5 and -1/1.5; this is -1.2<z<-0.67 or probability of 0.1364
f. this is a z between 2.3/1.5 and 4 or  probability of 0.0626
g.  this is a z between -1.2/1.5 and +0.9/1.5 or between -0.8 and +0.6 or probability of 0.5139
h. 80th percentile is where z is +0.84, so that (x-mean)/1.5=0.84 or (x-mean=1.26), or x=mean+1.26, so that x=9.26 oz.
i.  5th percentile is z=-1.645, and x-mean = -2.47 so that x=8-2.47 or 5.53 oz.
j. interquartile is z.25 and z.75 which is -0.675 to +0.675 for z or +/- 1.01 oz from the mean or (6.99, 9.01).  The +/- 1.01 is z* sd.