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