Specialist Statistics Textbook Question HELP!

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I need help please for this question

Two different farms, farm A and farm B grow wheat, and the wheat can only be sold if it is above 10cm.
Wheat above 10cm is called tall wheat and any wheat below 10cm is short wheat.
Standard deviation is 3.1.
Farm A claims that it produces more 'tall wheat' than farm B. Write the null and alternative hypothesis for this, and test this claim using the 5% significance level.

Two samples are taken:
In a sample of 12, the average height of Farm A's wheat is 11.3
In a sample of 12, the average height of Farm B's wheat is 11.23



Thanks in Advance!