Question

500 men took dip in a tank which is 80 m long, 50 m board what is the rice in water level if the average displacement of water by a man is 4 metre³

Answer 1

Level of water in the tank = h
Now.,
The amount of water rises in the tank = displacement of water taken by 500persons.

80*50*h = 500*4
4000h = 2000
H = 2000/4000 m
1/2m = 100/2cm = 50cm

50*10mm = 500mm
Thus,the rise of level of water in the tank is 500mm....... 

Hope it help you............. 

Answer 2

$\textbf{\huge\underline{\underline\red{solution} : - }} \\ \\ \bold{\underline\purple{here \: we \: know}} \\ \\ \red{1.} \bold \blue{ \: length \: (l)\: of \: rectangle \: \: tank \: is \: 80 \: m .} \\ \red{2.} \bold \blue{ \: breadth \:( b)\: of \: rectangle \: tank \: is \: 50 \: m.} \\ \red{3.} \bold \blue{ \: displacement \: of \: water \: by \: a \: one \: } \\ \bold \blue{person \: in \: a \: tank \: is \: 4 \: {m}^{3} .} \\ \\ \underline \bold\red{so \: \:displacement \: of \: water \: in \: a \: tank \: by \:} \\ \underline \bold\red{ 500 \: persons } = \blue{500 \times 4 = 2000 \: }\bold\blue{ {m}^{3} \: \: \: \: ..(1)} \\ \\ \underline \bold \purple{let \: height \: of \: rectangular \: tank \: is \: h} \\ \\ \underline\bold\blue{to \: find \: volume \: of \: water \: in \: tank} \\ \\ \underline \bold \red{volume\: of \: rectangular \: tank \: } = \bold \purple{ l\times b\times h} \\ \\ \bold \red{v.o.r.t} = \bold \purple{80 \times 50 \times h} \\ \\ \bold \red{v.o.r.t} = \bold \purple{(4000 \times h \: \: ) {m}^{3} \: \: \: ..(2) } \\ \\ \underline\bold\blue{as \: we\: know} \\ \\ \underline\bold\purple{volume \: of \: raised \: water \: in \: rectangular } \\ \underline\bold\purple{tank \: is \: equal \: to \: displacement \: of \: water \: in } \\ \underline\bold\purple{ tank\: by \:500 \: person .} \\ \\ \underline\bold\red{hence} \\ \\ \bold\red{volume \: of \: raised \: water \: in \: rectangular } \\\bold\red{tank \:} = \bold\purple{ displacement \: of \: water \: in } \\ \bold\purple{ tank\: by \:500 \: person .} \\ \\ = > \bold \blue{4000 \times h} = \bold \blue{2000} \\ \\ = > \bold \blue{h} = \bold \blue{ \frac{2000}{4000}} = \bold \blue{ \frac{1}{2} } = \bold \blue{0.5 \: m\:=\:50\:cm} \\ \\ \underline \bold\red{Hence \: \purple{0.5 \: m } \: level \: of \: water \: rise \: in \: tank.}$