Question

mean of 75 numbers, if the mean of 45 of them is 18 and the mean of the remaining ones is 13​

Answer 1

Answer:

$total \: no \: are \: = 75 \\ letsum \: be \: x \: \\ therefore \: x \div 75 = mean \\ now \: given \: let \: x1 \: be \: sum \: of \: 45 \: numbers \: and \: x2 \: be \: sum \: of \: rest \: 30 \: numbes \\ now( \: x1 \div 45) \: + (x2 \div 30) = mean\: of \: 75 \: numbrs \: \\ put \: the \: mean \: value \: of \: both \: \\ therefore \: x1 = 45 \times 18 = 810 \: and \: x2 = 30 \times 13 = 390 \\ x1 + x2 = 1200 \\ 1200 \div 75 = 16 \\ hence \: answer \: is \: 16$above explained