350 people visited a zoo the zoo has four types of tickets the manager wants a sample of size 30, stratified by ticket type. how man teenagers should be in the sample *see attached*

10

Step-by-step 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)

the answer   is 200

step-by-step explanation:

this is a problem about poisson probabilities.   i don't know if you've

already studied poisson distributions, or if you have a place to look

to read more about the subject.  

here's how you can see a poisson distribution coming.   when there are

a lot of events that may happen at any time (or any place), and when

you're counting how many of them happen at a particular time (or a

particular place), and each event is independent of the others, then

the result is a poisson distribution.   this is roughly true for the

chocolate chips; one chip being in a cookie has only a small effect on

the probability that another chip will be in the cookie.

once you know you have a poisson distribution, you know a lot.   there

is only one parameter to a poisson distribution, so if you know the

mean, you know everything.   the form of the distribution is

  probability of n chips = {[e^(-x)]*(x^n)} / (n! )