Please don't take this down, I genuinely do not understand it!

Let X and Y be the following sets:

X = {5,10,15}
Y = {3,6,9,12,15}

Which of the following is the set X∪Y ?
CHOOSE ONE ANSWER
A. {3,6,9,12,15}
B. {5,10,15}
C. {3,5,6,9,10,12,15}
D. {}

This race was first held in 1953 on august 16th. every decade the race finishes with a festival. how many years is this?

Use the frequency distribution, which shows the number of american voters (in millions) according to age, to find the probability that a voter chosen at random is in the 18 to 20 years old age range. ages frequency 18 to 20 5.9 21 to 24 7.7 25 to 34 20.4 35 to 44 25.1 45 to 64 54.4 65 and over 27.7 the probability that a voter chosen at random is in the 18 to 20 years old age range is nothing. (round to three decimal places as needed.)

If the speed of an electromagnetic wave is 100,000 cm/s and its wavelength is 100 cm, what is its frequency? a) 100,000 cycles per second (hz) b) 1 × 10-3 cycles per second (hz) c) 10,000,000 cycles per second (hz) d) 1,000 cycles per second (hz)