Answer: 10
Explanation:
Given the following :
Total number of visitors = 350
Sample size = 30
Number selected from each strata is given by:
(Strata size ÷ Total population) × sample size
From the cumulative frequency distribution :
Child - 90
Teen - (210 - 90) = 120
Adult - (350 - 210) = 140
Senior = 0
Strata size of teen = 120
Therefore, number of teen selected is ;
(120 ÷ 350) × 30
0.3428571 * 30 = 10.26 (10 visitors)