Step 1: Understanding the clear vision range
The clear vision range of the normal human eye is generally defined as the distance within which the eye can focus clearly without any corrective lenses. This is typically from a minimum distance of 25 cm to infinity.
Step 2: Why the other options are incorrect
- (A) 25 cm to 100 m: This is incorrect as the clear vision of a normal eye extends beyond 100 m and goes to infinity.
- (C) 50 cm to 2 km: This is incorrect because the minimum clear vision distance for a normal eye is 25 cm, not 50 cm.
- (D) 25 cm to 10 m: This is incorrect as the range of clear vision for a normal eye goes much beyond 10 m, all the way to infinity.
Thus, the correct answer is option (B) 25 cm to infinity.
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.