According to an on-line dating website, 20% of the couples who are in committed relationships met on-line. suppose you know 15 couples in a committed relationship. what is the expected number of couples who met on-line? what is the standard deviation?

15/x = 20/100
15*100 = 20*x
1500 = 20x
1500/20 = 20x/20
75 = x

15/75 = 20/100

the expected number of couples who met online is 75

All of the following are equivalent except for 0.4. the first choice has a value of 4% which when converted to its decimal equivalent is 0.04. this was obtained by dividing the percent value by 100. the value 0.4 is actually equivalent to 40% and not 4%. this makes it the odd value out of the three choices.