A farmer has a reservoir with vertical sides and a surface area of 2.5 ac. 

Following the rainy season, the reservoir is filled to a depth of 3.0 m. During 

the dry season the reservoir loses 2.5 in. of water per week (wk) to evaporation. 

If the average irrigation demand during the dry season is 0.23 ac-ft per day, how many

weeks can the farmer irrigate from the reservoir ? 

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