4. Two cylinders have dimensions in the ratio of 2:3. The smaller cylinder has a surface area of 16 cm. What is the surface area of the larger cylinder?

(cross multiply)

2:3

16:X

2X=16×3

2x=48

x=48÷2

x=24

solution:

→c= a b , that is product of a and b is possible only when when a is m × n matrix and b is n × p matrix.

that is, number of columns of a= number of rows of b.

so, size of matrix , c= a b is , if a = (m × n)matrix

b= (n × p)matrix

then a b = [ (m × n)matrix] ×[   (n × p)matrix ]

→→c= a b= [m × p ] matrix

→→size of product a b will be equal to = number of rows of a × number of columns of b