Solve Apps: Trigonometric Equations
-The Weekly Sales in Thousands of Items

Multiple Choice

Solve Apps: Trigonometric Equations
-The weekly sales in thousands of items of a product has a seasonal sales record approximated by $\mathrm { n } = 84.37 + 15 \sin \frac { \pi \mathrm { t } } { 24 }$ ( $\mathrm { t }$ is time in weeks with $\mathrm { t } = 1$ referring to the first week in the year) . During which week(s) will the sales equal 91,870 items?

A) week 4 , week 20 , and week 52
B) week 30 and week 47
C) week 4 and week 47
D) week 21 and week 30