Question

the mean of 15 observations was 250.it was detected on checking that the value of 165 was wrongly copied 115 for computation of mean.find the correct mean.

Answer 1

(x1+x2+........+x15)÷15=250
or x1+x2+........+x15=250×15
=3750
or x1+x2+...... +x14+115=3750
or x1+x2+....... +x14=3750-115
=3635
therefore the correct mean =(3635+165)÷15
=253.3 answer