The following table shows the distribution of household incomes in 2010 for a sample of 1,000 households in a country with incomes up to $100,000.

Income ($1,000)	10	30	50	70	90
Households	250	270	180	150	150

Compute the expected value and the standard deviation of the associated random variable X. (Round your answers to the nearest $1,000.)=$ =$ If we define a "lower-income" family as one whose income is more than one standard deviation below the mean and a "higher-income" family as one whose income is at least one standard deviation above the mean, what is the income gap between higher- and lower-income families in the country? (Round your answer to the nearest $1,000.)$