There is a bag with only red marbles and blue marbles. The probability of randomly choosing a red marble is 3/7
There are 12 red marbles in the bag and each is equally likely to be chosen.
Work out how many marbles in total there must be.

Find the value of the cosine for angle a

Suppose there is a simple index of three stocks, stock abc, stock xyz, and stock qrs. stock abc opens on day 1 with 4000 shares at $3.15 per share. stock xyz opens on day 1 with 5000 shares at $4.30 per share. stock qrs opens on day 1 with 6000 shares at $4.60 per share. the price of stock abc on day 8 begins at $3.50. the price of stock xyz on day 8 begins at $3.90. stock qrs opens on day 8 with a price of $4.50 per share. assume that each stock has the same number of shares that it opened with on day 1. what is the rate of change of this simple index over 1 week?

The value √10 and √15 are plotted on the number line