Baby talk: In a sample of 69 children, the mean age at which they first began to combine words was 16.44 months. with a standard deviation of 9.47 months. Part 1 out of 2 Construct a confidence interval for the mean age at which children first begin to combine words. Round the answers to two decimal places. A 98% confidence interval for the mean age is:

A 98% confidence interval for the mean age is:

= ( 13.78, 19.10) months

Step-by-step explanation:

Confidence interval can be defined as a range of values so defined that there is a specified probability that the value of a parameter lies within it.

The confidence interval of a statistical data can be written as.

x+/-zr/√n

Given that;

Mean x = 16.44 months

Standard deviation r = 9.47 months

Number of samples n = 69

Confidence interval = 98%

z(at 98% confidence) = 2.33

Substituting the values we have;

16.44+/-2.33(9.47/√69)

16.44+/-2.33(1.140054028722)

16.44+/-2.656325886922

16.44+/-2.66

= ( 13.78, 19.10) months

Therefore, A 98% confidence interval for the mean age is:

= ( 13.78, 19.10) months

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! )

answer: expected value of x = 1.0

step-by-step explanation:

p(x=0) = 0.25

p(x=1) = 0.50

p(x=2) = 0.25

expected value for x = 0×0.25 + 1×0.5 + 2×0.25 = 1.0