Question
The average age of a group of
five friends is 78 years. If a friend, aged 48 years, is replaced by another friend, then the average age of each friend in the group will increase by 4 years. Find the age of the friend who was replaced.Solution
ATQ,
Sum of the ages of 5 friends, initially = 5 X 78 = 390 years Let the age of the new friend who joined the group = 'y' years Therefore, 390 - 48 + y = 5 X (78 + 4) Or, 'y' = 410 - 342 = 68 Therefore, age of the new friend = 68 years Alternate Solution Age of the new friend = age of the friend replaced + increase in average age X number of friends So, age of the new friend = 48 + 5 X 4 = 48 + 20 = 68 years
79, 248, ?, 225, 125, 206
840, 2520, 630, 3150, ?, 3675
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24 36 72 108 216 ?
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24, 35, 57, 90, 134, ? What value should come in the place of (?) in the following number series?
24, 45, 133, 531, 2655, ?
What value should come in the place of (?) in the following number series?
1.5, 2.5, 4, 6, ?, 11.5
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