johnsonjermille9
johnsonjermille9 johnsonjermille9
  • 20-01-2021
  • Mathematics
contestada

The average age of three people running for election is 42. A fourth person joins the race and the average drops to 40. What is the fourth person's age?​

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BigBrainBigMuscle
BigBrainBigMuscle BigBrainBigMuscle
  • 20-01-2021

Call the four people [tex]abc[/tex] and [tex]d[/tex].

We know:

[tex]\frac{a+b+c}{3}[/tex][tex]=42[/tex]

and

[tex]\frac{a+b+c+d}{4}[/tex][tex]=40[/tex]

Thus:

[tex]a + b + c = 126[/tex]

[tex]\frac{126+4}{4} = 40[/tex]

[tex]126 + d =160[/tex]

[tex]d = 34[/tex]

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