2 cu(s) + co2(g) → 2 cuo(s) + c(s) which statement is true?.

Abag contains even and odd numbered balls in the ratio of 3: 7, respectively. for each of the following, what is the probability of drawing an even-numbered ball? the total number of balls is 240 and 30 of the odd-numbered balls are renumbered by multiplying the numbers by 4.

Raul has one solution that is 20% acid by volume and one solution that is 50% acid by volume. he plans to mix together some of each solution to create 30 milliliters of a solution that is 40% acid by volume. how many milliliters of the 20% acid solution should raul use to create the 40% acid solution? can someone explain this to me? i know that the answer is 10 milliliters, but i don't know how to get it.

Mary wants to determine the average height of the plants in her plant collection. she measures them and finds their heights are 8 inches, 7.5 inches, 11 inches, 6.5 inches, and 14 inches. what is the average height of her plants?