Assume that the thermometer readings are normally distributed with a mean of 0 degrees C and a standard deviation of 1.00 degrees C. A thermometer is randomly selected and tested. The probability of getting a reading between -1.39 degrees C and 1.69 degrees C is ____

Question

kropot72 · Answer

Do you know how to get the z-scores for -1.39 and 1.69 from the formula:
$$\large z=\frac{X-\mu}{\sigma}$$

anonymous · Answer

The main thing that I am stuck on is how to get the sigma

kropot72 · Answer

Sigma is the standard deviation, which is given as 1 degree C.

anonymous · Answer

Ok, so would I use this formula to obtain the probability of the reading?

kropot72 · Answer

You need to find the two values of z-score and then use a standard normal distribution table to work out the required value of probability.