Question

A concert that features different singing groups will be held at a Municipal Hall. The concert will start with a solo performance, followed by a duet, then a trio, and so on with the last performance coming from a choir with 30 members. How many people will perform at the concert? (problem-solving)

Answer 1

Explanation:

this is the problem to sum the numbers 1 ... n.

remember the old trick by adding

n + 1

n-1 + 2 = n + 1

n-2 + 3 = n + 1

...

and doing this n/2 times, giving us a sum

n×(n+1)/2

for n = 30 we get

30×31/2 = 15×31 = 465

so, 465 people will perform.