A group of 20 students are sitting in a circle. Each shakes hands with exactly 3 neighbours. How many handshakes occur?
30
If every one of the \(n = 20\) students shakes hands with exactly \(d = 3\) others, then the sum of degrees is \(n \times d = 20 \times 3 = 60\).
Each handshake is counted twice in the degree sum (once for each participant), so the number of distinct handshakes is
\(\dfrac{n \times d}{2} = \dfrac{60}{2} = 30\).
Hence the correct answer is 30.
10 friends went for dinner and planned to split Rs. 200 equally. 2 didn't pay. How much did each of the rest pay?
In a pet shop, there are only parrots and rabbits. Total heads = 40, and total legs = 100. How many parrots are there?
The population of a village increased by 10% in the first year and 20% in the second year. What is the total percent increase after 2 years?
The rectangle represents a set of calculations that are common across all the given equations. Identify the calculations involved and solve the fourth equation on the same basis:
$7 \blacksquare 4 = 27/4$
$6 \blacksquare 1 = 5$
$4 \blacksquare 3 = 11/3$
$a \blacksquare b = ?$