# Homework Help: A question about statistics

1. Nov 18, 2012

### Artusartos

Suppose $$X_1, X_2, ... , X_10$$ is a random sample on a random variable X which has a Poisson distribution with mean $$\theta$$. Say the realized value of the sample mean is 0.5, i.e., $$n \bar{x} = 5$$. Suppose we want to compute the confidence interval $$(\bar{\theta}, \underline{\theta})$$. Using the table (for a poisson distribution), show that 0.2 and 0.3 bracket $$\underline{\theta}$$ and that 0.9 and 1.0 bracket $$\bar{\theta}$$. If R is available, us the R function poissonci.r to compute the solutions ot the equations.

I want to use R, but I'm not sure how...

I tried to put the commands:

$$poi(4, 10 \cdot 0.2)$$
$$poi(4, 10 \cdot 0.3)$$
$$poi(5, 10 \cdot 0.9)$$
$$poi(5, 10 \cdot 1.0)$$

...because that's what they do in my textbook. But, for some reason, I don't know how to type the dot (between 10 and 0.2 for example) in R...

So can anybody help me please?