# Math Help - finding the shape,sd and mean

1. ## finding the shape,sd and mean

im having trouble finding (basically everything) i cant seem to figure out the problem with the given numbers.

In the problem it says that 39% of housholds have a dog in your city and that you takes a simple random sample of 50 households.

basically wer have to describe the shape, mean, and standard deviation.

i assume the .39 is the population mean and 50 is the sample observtion. i could be all wrong though. help please!

2. Originally Posted by lunaj
im having trouble finding (basically everything) i cant seem to figure out the problem with the given numbers.

In the problem it says that 39% of housholds have a dog in your city and that you takes a simple random sample of 50 households.

basically wer have to describe the shape, mean, and standard deviation.

i assume the .39 is the population mean and 50 is the sample observtion. i could be all wrong though. help please!
The number of a of households with a dog in a sample of $50$ has a binomial distribution $B(50,0.39)$ , which we know has mean $0.39 \times 50=18.5$, and a standard deviation of $\sqrt{50 \times 0.39 \times (1-0.39)}$

RonL

3. thank you so much!

im taking the course online so it keeps getting harder and harder. i dont think we've gone over the binomial thing or how to find a mean the way you did. so far its been given to us or there are multiple numbers and we find the mean.