Question

Assume that the readings at freezing on a batch of thermometers are Normally distributed with mean 0°C and standard deviation 1.00°C.

Find the temperatures that make up the middle 90% of all temperature readings.

From °C to °C Round to 2 places.

Answer 1

Now ,

.............(I)

From standrad normal distribution table , ................(II)

From (I) and (II) , we get ,

z=1.64 and -z=-1.64

Therefore , the temperatures that make up the middle 90% of all temperature readings from -1.64°C to 1.64°C