How to find probabilities using normal distribution

Question

Pumpkins from a large crop are found to have a mean weight of 4.1kg with a standard deviation of 0.45kg. Calculate the probability that a pumpkin weighs between 3.5 and 4.5 kg.

I worked out that the z value is -2.444 (rounded to 3dp). The correct probability should be 0.4927, but I get 0.4928 from the table. How do I get the correct answer?

Answer 1

I don’t get that at all. I get two z scores, one for each side:

$z = (4.5 - 4.1)/0.45 = 0.8888$ with probability 0.3131

$z = (3.5 - 4.1)/0.45 = -1.3333$ with probability (for $z=1.3333$) 0.4087

For a total probability of 0.7218

Also, I checked my answer using a computer:

> pnorm(4.5, mean = 4.1, sd = 0.45) - pnorm(3.5, mean = 4.1, sd = 0.45)
[1] 0.7217574