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Question
If class mark is 10 and class width is 6 then find the class.
Solution
Let x be the upper class limit and y the lower class limit.
class mark = 10 ..[given]
class mark = `(x + y)/2`
10 = `(x + y)/2`
x + y = 20 ...(i)
class width = 6 ...[given]
x - y = 6 ....(ii)
Adding equation (i) and (ii)
x + y = 20
+ x - y = 6
2x = 26
x = `26/2`
x = 13
Putting the value x = 13 in equation (i),
x + y = 20
13 + y = 20
y = 20 -13
y = 7
∴ the class is 7-13.
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