The Precision Scientific Instrument Company manufactures thermometers that are supposed to give readings of 0 degrees Celcius at
the freezing point of water. Tests on a large sample of these thermometers reveal that at the freezing point of water, some give readings below 0 degrees celcius (denoted by negative numbers) and some give readings above 0 degrees celcius (denoted by positive numbers). Assume that the mean reading is 0 degrees celcius and the standard deviation of the readings is 1.00 degrees celcius. Also assume that the frequency distribution of errors closely resembles the normal distribution. A thermometer is randomly selected and tested. Find the temperature reading corresponding to the given information.
If 7% of the thermometers are rejected because they have readings that are too low, but all other thermometers are acceptable, find the temperature that separates the rejected thermometers from the others.
I know the answer, but do not how to solve the problem. answ-->-1.48
Find the z-value with a left tail of 7%:
invNorm(0.07) = -1.48
Find the termperature deviation that corresponds to that z-value:
x = z*s + u
x = -1.48*1 + 0 = -1.48
Convert 1 and 1/2 to eights to make it easier to subtract. 1 4/8 add 1 to 4/8 12/8 then subtract that by 7/8 straight across the numerator. That then equals 5/8
