Question

average age of seven friends is 32 in 2010. what is their average in 2015​

Answer 1

Answer:

37

Step-by-step explanation:

average age now = 32

sum of their ages now is 32×7= 224

in 2015, the age of all friends will increase by 5

therefore, 224+7×5=259

Average age now, 259/7

=37

Ans= Average age of 7 friends in 2015 is 37

Answer 2

Given,

The average age of 7 friends in 2010 is 32.

To find,

The average age in 2015.

Solution,

The average age of 7 friends will be given as,

$average = \frac{sum \hspace{3} of\hspace{3} the\hspace{3} ages \hspace{3}of \hspace{3} 7 \hspace{3} friends}{number\hspace{3} of\hspace{3} friends\hspace{3} (7)}$     ...(1)

In 2010, the average = 32.

⇒ $32 = \frac{sum \hspace{3} of\hspace{3} the\hspace{3} ages \hspace{3}of \hspace{3} 7 \hspace{3} friends}{7}$

On rearranging, we can find the sum of their ages in 2010, as,

$sum \hspace{3} of\hspace{3} the\hspace{3} ages \hspace{3}of \hspace{3} 7 \hspace{3} friends}= 32 \times 7$

⇒ $sum \hspace{3} of\hspace{3} the\hspace{3} ages \hspace{3}of \hspace{3} 7 \hspace{3} friends}= 224$

Now, in the year 2015, the age of each of these 7 friends will increase by 5 years.

It means, we have to add 5 to each of their ages, or we can simply add 7 times 5 with 224 (sum of ages in 2010), to get the sum of their ages, in 2015. Thus,

$sum \hspace{3} of\hspace{3} the\hspace{3} ages \hspace{3}of \hspace{3} 7 \hspace{3} friends \hspace{3} in \hspace{3} 2015}= 224 +(7 \times 5)$

⇒ $sum \hspace{3} of\hspace{3} the\hspace{3} ages \hspace{3}of \hspace{3} 7 \hspace{3} friends \hspace{3} in \hspace{3} 2015}= 224 +35$

⇒ $sum \hspace{3} of\hspace{3} the\hspace{3} ages \hspace{3}of \hspace{3} 7 \hspace{3} friends \hspace{3} in \hspace{3} 2015}= 259$

So, in 2015, the average can be found using the formula from equation (1),

$average = \frac{sum \hspace{3} of\hspace{3} the\hspace{3} ages \hspace{3}of \hspace{3} 7 \hspace{3} friends}{number\hspace{3} of\hspace{3} friends\hspace{3} (7)}$

⇒ $average = \frac{259}{7}$

⇒ average = 37.

Therefore, the average age of seven friends in 2015 will be 37.