The perimeters of 5 squares are 24 cm, 32 cm, 40 cm, 76 cm and 80 cm respectively. The perimeter of another square equal in area to the sum of the area of these square is

Clearly first we need to find the areas of the given squares, for that we need its side.
Side of sqaure = Perimeter/4
So sides are,  

                    $$\begin{gathered} \left(\frac{24}{4}\right) , \left(\frac{32}{4}\right) , \left(\frac{40}{4}\right) , \left(\frac{76}{4}\right) , \left(\frac{80}{4}\right) \\ =6, 8, 10, 19, 20 \\ Area of new square will be \\ = \left[6^2+8^2+{10}^2+{19}^2+{20}^2\right] \\ = 36+64+100+361+400 \\ =961c{m}^2 \\ Side of new Sqaure =\sqrt{961} \\ =31cm \\ Required perimeter = \left(4\times 31\right) \\ =124cm \end{gathered}$$