Finding a new standard deviation from an old one

Question

This is the question they gave me.

The average domestic economy car gets around 31.5 miles per gallon (MPG) with a standard deviation of 1.16. Suppose domestic manufacturers all vow to increase fuel economy over the next 2 years. If successesful, 2.7 is added to every observation in the dataset. What is the new standard deviation?

I'm not sure how to find a new standard deviation with so much info missing. I don't know how many cars were tested or anything.

Multiplying the old standard deviation by 2.7 gives me 3.132 which is one of the possible answers but I feel that's too easy and isn't correct.

Answer 1

The standard deviation of a data set measures how the data is spread out.

Increasing each observation in the data set by the same amount does not change the spread of the data.

So, the "new" standard deviation is the same as the "old" standard deviation.