The average marks of boys in a class is 40 and that of girls is 45 . The average marks of both boys and girls combined is 42 . Then the percentage of boys in the class is

Step-by-step solution

Let the number of boys and girls in the class are (m ) and (n ) respectively, so according to given informations, Total marks of boys (=40 ~m ) and total marks of girls (=45 n ) and total marks of boys and girls (=42(m+n) ) ( array ll & 40 m+45 n=42(m+n) & 2 m=3 n m 3 = n 2 = (let) & m=3 and n=2 array ) So, the percentage of boys in the class is ( aligned & m m+n 100 & = 3 3 +2 100= 3 5 100=60 % aligned ) Hence, option (a) is correct.