Question

The average marks scored by a student in a test of 6 subjects is 18. The sum of

the marks scored by him in 5 subjects is 86. Then the marks scored by him in

the sixth subject is
please explain it and solve
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Answer 1

Let marks scored by him in 5 subjects be M5 and that in the 6th subject is M6
Now average marks = (M5 + M6)/6
18*6 = M5 + M6
Also M5 is given as 86
Therefore, 108 = 86 + M6
=> M6 i.e. marks scored in the 6th subject is = 108-86 = 22

Answer 2

Answer:

Marks scored in the sixth subject  = 22

Step-by-step explanation:

Given,

The average marks in 6 subjects  = 18

Total marks scored in 5 subjects = 86

Required to find,

The mark in the sixth subject

Recall the formula,

Average = $\frac{Sum \ of \ observations}{Total \ no. \ of \ observations}$

∵ Average mark of 6 subjects = $\frac{Total \ marks \ in\ 6 \ subjects}{6}$ = 18

∴ Total marks in 6 subjects = 18 x 6 = 108

Also given,

Total marks in 5 subjects = 86

∴ Marks scored in the sixth subject = Total marks in 6 subjects - Total marks in 5 subjects

= 108 - 86

= 22

Hence,

Marks scored in the sixth subject  = 22