Question

3. A new organic pest control formula is being tested on potato plants to see whether it can reduce the level of potato beetle infestation. The mean number of beetles per untreated plant is 5. It is hoped that the new formula may reduce this infestation rate. State the appropriate null and alternate hypotheses.

Answer 1

Since we have to test the effect of new organic pest control formula was effective or not in reducing the level of beetle infestation on potato plants we would use a paired t test .

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Therefore null and alternate hypothesis here are

Null Hypothesis : The population mean of the differences of paired observations is equal to zero. [ New organic pest control formula is not effective.]

Vs

Alternative hypothesis (two-sided): The population mean of the differences of paired observations is not equal to zero. [ New organic pest control formula is effective. ]

Paired t Test are used when we take observations twice on the same subject twice i.e. here we are taking observations on the same plant before doing pest control and after applying the pest control . [ our aim is to reduce the infestation rate i.e. no of beetles are expected to be reduced after pest control new formula is applied ]

Symbolically we denote the hypothesis as follows :

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Where,

x and y observations are the number of beetles per untreated ( before treated ) and then after treated plants respectively .

These are the appropriate hypothesis .

So if the number of beetles are reduced we can say that the new formula is effective .

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