Question 1031185
The question asks for two volumes:
•The volume of the tank's capacity
• The volume of the concrete tank

Through the given information, we can first find the tank's capacity (the amount of space it can hold inside) through the given information.
The question says the tank is INTERNALLY 1m wide, 2m long and 1.5m deep, that has already given us the values for the tank's capacity, we can deduce (through the equation of volume:
let the tank's capacity be c{{{c=1*2*1.5=3m^3}}} Convert this value to liters to get the answer in the requested unit of measure.
{{{3m^3=3000L}}}

Now, we must also find the concrete tank's volume, and now keep in mind only the tank's concrete.
it mentions that the concrete is 10 cm thick, and since we are calculating the entire tank, we add the the thickness of concrete to the sides (convert it to m to make the method simpler, which will be 0.lm).
1m wide + 0.2m, we are adding 20  cm here since we are adding for both sides of the tank.
2m long + 0.2m, the same situation here.
1.5m deep + 0.1m, we only add 10 cm here since the question says an open concrete tank, so the assumption is it has only one side on the vertical axis (meaning it has no cap).
The values are 1.2m,2.2m,1.6m
multiply them and you will get the volume of the tank, let the volume of the tank be t {{{t=1.2*2.2*1.6=4.224m^3}}}, 
but that is the entire volume, we only need the concrete's volume, so, logically, we may subtract the tank's capacity from the total volume to acquire only the concrete's volume:
{{{t-c=4.224m^3-3m^3=1.224m^3}}}
The concrete's volume is {{{1.224m^3}}}