weighted mean = sum of the multiplication of frequency and value /sum of frequency
sum of frequency = 5 + 5 + 5 + 21 = 36
sum of the multiplication of frequency and value = (16 x 5) + (20 x 5) + (16 x 5) + ( 5 x 21) = 365
365/36 = 10.1
the tenth is the first number after the decimal place. To convert to the nearest tenth, look at the number after the tenth (the hundredth). If the number is greater or equal to 5, add 1 to the tenth figure. If this is not the case, add zero
