The average height of 5 boys is 175 cm. A sixth boy joined the group and the average height of all the boys in the group now increased by 1 cm. The height of the sixth boy is:

180 cm 181 cm 175 cm 179 cm

181 cm

Sum of heights of 5 boys = 5 x 175 = 875 cm Sum of heights when 6th boy joins the group = 6 x 176 = 1056 cm Height of 6th boy = 1056 - 875 =181 cm