A 3 digit number is written on a piece of paper. What's the probability that it starts with a 3?

A 3 digit number can only start with 1-9. 3 is one number in this so therefore there’s a 1/9 chance it will start with a 3. As a decimal it’s .1 repeating probability.

You have 2 sides that are 2 cms and you have 6 sides that are 1/2 cm and you have 4 sides that are 1 cm. the smallest sides are 1/2 the medium sized sides are 1 and the smallest are 1/2. so to find the perimeter you have to add them all up together so your answer will be 11 cm's