Question

a rectangular pit 1.4 long,90cm broad and 70cm deep was dug and 1000 bricks each of base 21cm by10.5cm were made from the earth dug out. find the height of each brick

2.how many wooden cubes of an edge 25cm in length can be cut out from a cuboidal log of size 2.5mby 0.5m by 50cm assuming that there is no wastage

3 a closed box is made up of 2cm thick wood with external dimention 84x75x64cm .find the volume of the wood required to make the box

4 a swimming pool is 50m length ,30m in breadth and 2.5m in depth .find the cost of cementing its floor and walls at the rate of rs 27per square metre

5 the floor of a rectangular hall has a perimeter 236,its height is 4.5m, find the cost of painting its four walls(doors and windows be ignored) at the rate of rs 8.40 per square metre

6 a cuboidal fish tank has a length of 30cm, a breadth of 20cm and a height of 20 cm, the tank is placed on a horizontal table and it is three quarters full of water, find the area of the tank which is in contact with water

7a box of nutties has a ribbon tied as 12cmby 18cm by 30cm with 32 cm for a bow . what length of ribbon was used

Answer 1

$$\begin{gathered} 2.Dimensionsofcuboid: \\ l=2.5m=250cm;b=0.5m=50cmandh=50cm \\ Edgeofcube:\hspace{0.17em}25cm \\ Asnnumberofcubescanbecutfromthecuboidsothevolumeofthesecubes=volumeofcuboid \\ n\times volumeofacube=volumeofcuboid \\ n=\frac{volumeofcuboid}{volumeofcube} \\ n=\frac{250\times 50\times 50}{25\times 25\times 25} \end{gathered}$$
$$\begin{gathered} n=\frac{625000}{15625}=40 \\ So,thenumberofcubescanbecutfromcuboidis40. \end{gathered}$$

$$\begin{gathered} 4.Dimensionsofswimmingpool: \\ l=50m;b=30m;depth\left(h\right)=2.5m \\ Areaoffourwallaandfloor=areaoffivefaces=2(l+b)h+l\times b \\ Putthevalues, \\ =2(50+30)\times 2.5+50\times 30 \\ =2\times 80\times 2.5+1500 \\ =400+1500=1900m^2 \end{gathered}$$
$$\begin{gathered} Nowthe\cos tofcementingitattherateofRs.27persquaremetre=1900\times 27 \\ =Rs.51,300 \end{gathered}$$