What's the lcm for 18, 27, 12? I got 648. Am not sure if it is correct. Can you please explain if it is correct or not?

Mary used 1/7 of a spool of ribbon to complete 4 projects. she used the same amount of ribbon on each project. how much ribbon did she use on each project?

Divide. write in the simplest form. 4 1/6 divided by 10

Weekly wages at a certain factory are normally distributed with a mean of $400 and a standard deviation of $50. find the probability that a worker selected at random makes between $450 and $500