Question

If the human body can withstand a maximum of 9720 units of IR rays when exposed to the sun continuously, then what is the maximum time in minutes that any person could stand in the sun without crossing the threshold limit of IR rays?

• A. 23
• B. 19
• C. 27
• D. 29

Hint:

From pie charts, first translate a slice's percentage into an actual rate (units per minute), then scale to the asked duration using a simple proportion.

Answer 1

The Correct Option is C

Step 1: Read the pie-chart share for IR rays. 
IR rays constitute \(10\%\) of the total solar radiation. 

Step 2: Convert percentage to per-minute units. 
Total rays per minute \(= 3600\) units (given). 
IR per minute \(= 10\%\) of \(3600 = \dfrac{10}{100}\times 3600 = 360\) units/min. 

Step 3: Use the threshold to compute time. 
Let \(t\) be the allowable minutes. Then 
\(\text{IR received in } t \text{ min} = 360 \times t \le 9720\). 
Solve: \(t \le \dfrac{9720}{360} = 27\). 

Step 4: Conclude (maximum whole minutes). 
Maximum permissible time \(= \boxed{27\text{ minutes}}\).