The fuel consumption of a ﬂeet of

**150 lorries**is approximately normally distributed with mean 15 mpg and sd 1.5 mpg.

(ii) What is the probability that the average consumption of a random sample of

**four lorries**exceeds 16 mpg?

I have an idea on how to solve the question, by using the standard normal distribution but how do I take into account that the question is asking for the consumption of four lorries, rather than 150?

Thanks for your time!