Question

Mean of numbers 71, 78, 75, 80, a, b, is 80
(a) find a+b
(b) if a-b =10 then find a and b

Answer 1

GIVEN,

Numbers= 71,78,75,80,a,b

mean=80

TO FIND,

a) a+b

b) a-b=10 , calculate a&b

SOLUTION,

a) as we know

MEAN= SUM OF NUMBER/ TOTAL NUMBER

substituting values,

MEAN= (71+78+75+80+A+B )/ 6

80*6= 304+ A+B

480= 304+A+B

176= A+B----------------------(i)

b) given a-b=10---------------(ii)

solving both equations i & ii

A+B=176

A-B=10

we get,

2A=166

A=83 putting value of A in (ii)

we get

A-B=10

83-B=10

B=73.

HENCE THE VALUES OF A& B ARE 83 & 73 respectively.