On the Navajo Reservation, a random sample of 214 permanent dwellings in the Fort Defiance region showed that 52 were traditional Navajo hogans. In the Indian Wells region, a random sample of 139 permanent dwellings showed that 23 were traditional hogans. Let p1 be the population proportion of all traditional hogans in the Fort Defiance region, and let p2 be the population proportion of all traditional hogans in the Indian Wells region.

(a) Find a 90% confidence interval for p1 – p2. (Use 3 decimal places.)

lower limit =

upper limit =