Question

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?

Answer 1

The expected number of couples who met online is 3, and the standard deviation is 1.94.

Step-by-step explanation:

To find the expected number of couples who met online, you can multiply the total number of couples by the percentage who met online. In this case, the expected number would be 15 couples * 20% = 3 couples.

To find the standard deviation, you can use the formula for the standard deviation of a binomial distribution: sqrt(n * p * (1 - p)). In this case, the standard deviation would be sqrt(15 * 0.2 * 0.8) = 1.94.

Answer 2

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