INSECTS AND PLANT DISEASES 85 



treat the seed for twelve acres, what is the total cost 

 of the treatment? 



12. How many bushels of oats at 30 cents will it 

 take to pay the cost of the treatment ? 



13. Suppose the treatment increases the yield 

 twenty bushels per acre, how much does the farmer 

 gain on his crop ? 



14. How much is gained per acre by the use of the 

 treatment ? 



15. What is the cost per acre of the treatment? 

 The cost of the treatment for a forty-acre field? For 

 a twenty- four-acre field? 



1 6. Pupils will furnish data for similar problems- 



