We can see from the question that:
1. The next formula models the percentage of households with interfaith marriage, I, after 1988:
2. The next formula models the percentage of households in which a person of faith is married to someone with no religion, N, x years after 1988:
And we need to find in which years more than 67% of households have had an interfaith marriage.
3. Then to find it, we can use the given formula for interfaith marriage as follows:
4. And now, we have to solve the equation for x as follows:
5. Now, we need to multiply by 4 to both sides of the equation as follows:
6. Since x is the number of years after 1988, then we need to sum 44 to 1988 as follows:
Therefore, we can conclude that more than 67% of households have an interfaith marriage in the year after 2032 (because in 2032 will be 67%).