Step 1: Earth Summit Overview
The Earth Summit, also known as the United Nations Conference on Environment and Development (UNCED), was a major international conference held in 1992 in Rio de Janeiro, Brazil. It focused on sustainable development, environmental protection, and social equity.
Step 2: Importance of the Earth Summit
The Earth Summit was a milestone in the global environmental movement, leading to the adoption of key agreements, including the Rio Declaration on Environment and Development, Agenda 21, and the establishment of the Commission on Sustainable Development.
Step 3: Why the other options are incorrect
- (A) 1991: The Earth Summit did not take place in 1991.
- (C) 1993: The Earth Summit was not held in 1993.
- (D) 1994: The event was already held in 1992.
Thus, the correct answer is option (B) 1992.
Find the unknown frequency if 24 is the median of the following frequency distribution:
\[\begin{array}{|c|c|c|c|c|c|} \hline \text{Class-interval} & 0-10 & 10-20 & 20-30 & 30-40 & 40-50 \\ \hline \text{Frequency} & 5 & 25 & 25 & \text{$p$} & 7 \\ \hline \end{array}\]
Two concentric circles are of radii $8\ \text{cm}$ and $5\ \text{cm}$. Find the length of the chord of the larger circle which touches (is tangent to) the smaller circle.