If a serum-lutein value <5.0 g/dL indicates that a participant is not taking lutein capsules, then what

Question:

If a serum-lutein value <5.0 μg/dL indicates that a participant is not taking lutein capsules, then what percentage of the placebo group is complying (not taking lutein capsules outside the study)? Assume that the old assay is correct and that the serum values can be measured exactly.

In 1999, 100 participants were randomized to lutein and 100 participants were randomized to placebo. Each participant had his or her blood analyzed using the old assay method in 2000 after taking the study capsules for 1 year.

The mean serum-lutein level in the active group was 7.0 ± 4.0 (mean ± sd) based on the old assay and is assumed to be normally distributed. The mean serum-lutein level in the placebo group was 2.0 ± 1.5 (mean ± sd) based on the old assay and is assumed to be normally distributed.