How can you change the concentration of a solution?

If you have 12 feet of string and you cut it into equal length of 5 inches each how much string will be left

Find all the angles that satisfy the equation cos(θ)=32

Given a binomial distribution variable with n=20 and p=0.60 find the following possibilities using the binomial table a) p(x < 13) b) p x > 15) c) p(x = 17) d) p(11 < x < 14) e) p(11 < x < 14)