state the null and alternative hypothsis

Online ads targeting children were said to have decreased at least 56% between May and August 2000. A sample of 100 ads selected during this period showed a 45% decrease in online ads targeting children. State the null and alternative hypotheses and carry out the test at the 1% level of significance.

Here, which one shud be the null hypothesis $\displaystyle H_0$, and which one should be $\displaystyle H_a$? I'm confused.

Re: state the null and alternative hypothsis

Quote:

Originally Posted by

**wopashui** Online ads targeting children were said to have decreased at least 56% between May and August 2000. A sample of 100 ads selected during this period showed a 45% decrease in online ads targeting children. State the null and alternative hypotheses and carry out the test at the 1% level of significance.

Here, which one shud be the null hypothesis $\displaystyle H_0$, and which one should be $\displaystyle H_a$? I'm confused.

Take a null hypothesis that the number of adds targeting children has decreased by 56%, and the alternative as the decrease is less than 56%.

However I don't think the data you have been given is adequate to construct such a test for a number of reasons.

CB

Re: state the null and alternative hypothsis

Quote:

Originally Posted by

**wopashui** Online ads targeting children were said to have decreased at least 56% between May and August 2000.

The claim being tested is always the "null hypothesis".

Quote:

A sample of 100 ads selected during this period showed a 45% decrease in online ads targeting children. State the null and alternative hypotheses and carry out the test at the 1% level of significance.

Here, which one shud be the null hypothesis $\displaystyle H_0$, and which one should be $\displaystyle H_a$? I'm confused.

Re: state the null and alternative hypothsis

so shud I make $\displaystyle H_0: P= 56%$, and $\displaystyle H_a: P<56%$, however,it's at least 56%, does it mean p>=56%