Answer and explanation:
To find : Calculate to the nearest 1/10th meter the length of the side of a 7th, 12th, and 30th hectare square plot.
Solution :
The area of the square is given by,
where s is the side length.
We know, 
1) The area of square plot is 7 hectare.
Area in meter square is 
Substitute the value in the formula,
Side nearest to 1/10th meter is 264.8 meter.
2) The area of square plot is 12 hectare.
Area in meter square is 
Substitute the value in the formula,
Side nearest to 1/10th meter is 346.4 meter.
3) The area of square plot is 30 hectare.
Area in meter square is 
Substitute the value in the formula,
Side nearest to 1/10th meter is 547.7 meter.
Take to total number of people attending and subtract the number of adults. The remainder are the children
2,451 - 745 = 1,706
Shade 0.08 3 times
In total that's 24 hundreths to shade
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Hope this helps!!