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Ira Lisetskai [31]
1 year ago
13

The mean age of a group of students is 16. John joins the group and the mean age changes to 18. How old is john ?

Mathematics
1 answer:
schepotkina [342]1 year ago
5 0

Answer:

John is 20 years old.

Step-by-step explanation:

Given the second mean is 18, it is equal to the first mean age plus John's unknown age. The sum is also divided by 2 because there are 2 values in the sum (1. John's age and 2. the mean, 16 yrs old).

Set up an equation: \frac{x+16}{2}=18

multiply both sides by 2: x+16=36

simplify: x=20

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Answer:

<em>In 5 years the product of their ages will be 208</em>

Step-by-step explanation:

The age of two children is 11 and 8 years.

Let's call x the number of years ahead.

We need to find when the product of their future ages is 208. The 11 years old child will be 11+x years old and the other child will be 8+x years, thus:

(11+x)(8+x)=208

Operating:

88+11x+8x+x^2=208

Simplifying:

x^2+19x-120=0

Factoring:

(x-5)(x+24)=0

Solving:

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The negative solution is not valid, thus x=5

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