At a party, everyone shook hands with everybody else. There were 4005 handshakes. How many people were at the party?
The number of handshakes between people is always the sum of 1+2+3+...+(n-1). n = number of people. Say there are 5 people, handshake between them will be 1+2+3+4 = 10 (try that with your friends 😀)
The sum of 1 to n of any number is (n(n+1))÷2. For example 1+2+3+4+5 = 15 and (5(5+1))÷2 = (5*6)÷2 = 15
So, to find the number of people at the party
(n(n+1))÷2 = 4005
Cross multiplying: n(n+1) = 4005x2 = 8010
Expanding the bracket: n² + n = 8010 n² + n - 8010 = 0
Solving that using the Almighty Formula (I don't think I need to go into that details)
n = 90 and -89
Ofcourse there can be negative people at the party so answer is 90 people
At a party, everyone shook hands with everybody else. There were 4005 handshakes. How many people were at the party?
The number of handshakes between people is always the sum of 1+2+3+...+(n-1). n = number of people. Say there are 5 people, handshake between them will be 1+2+3+4 = 10 (try that with your friends 😀)
The sum of 1 to n of any number is (n(n+1))÷2. For example 1+2+3+4+5 = 15 and (5(5+1))÷2 = (5*6)÷2 = 15
So, to find the number of people at the party
(n(n+1))÷2 = 4005
Cross multiplying: n(n+1) = 4005x2 = 8010
Expanding the bracket: n² + n = 8010 n² + n - 8010 = 0
Solving that using the Almighty Formula (I don't think I need to go into that details)
n = 90 and -89
Ofcourse there can be negative people at the party so answer is 90 people
Answer: 90
BY Riddles Repository - Answers
Warning: Undefined variable $i in /var/www/tg-me/post.php on line 283
Traders also expressed uncertainty about the situation with China Evergrande, as the indebted property company has not provided clarification about a key interest payment.In economic news, the Commerce Department reported an unexpected increase in U.S. new home sales in August.Crude oil prices climbed Friday and front-month WTI oil futures contracts saw gains for a fifth straight week amid tighter supplies. West Texas Intermediate Crude oil futures for November rose $0.68 or 0.9 percent at 73.98 a barrel. WTI Crude futures gained 2.8 percent for the week.
However, analysts are positive on the stock now. “We have seen a huge downside movement in the stock due to the central electricity regulatory commission’s (CERC) order that seems to be negative from 2014-15 onwards but we cannot take a linear negative view on the stock and further downside movement on the stock is unlikely. Currently stock is underpriced. Investors can bet on it for a longer horizon," said Vivek Gupta, director research at CapitalVia Global Research.
