500 people were surveyed and asked whether had donated food or money to local charities in the past year. 80 had donated food, 150 had donated money, and 45 had donated both. what is the probability that a person chosen and random has donated food or money? express your answer as a decimal rounded to the nearest hundredth.

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