(Same question.) A sample of 18 male students was asked how much they spent on books this semester. The sample variance was 35.05. Find a 90% lower confidence interval estimate for the population variance of the mount spent on textbooks by male students. If lower bound is zero, type "0". If lower bound is -oo, type "negative infinity". If upper bound is one, type "1". If upper bound is +oo, type "positive infinity".