# Candle hour!

It was lucky that I had purchased two candles. Mother had asked me to buy some tea-leaves from the grocer. At the grocer, the candles caught my eyes and I purchased two of them although I had no need for them.

The candles were of the same length but of different thickness. The grocer told me that the fat one would burn for five hours while the slender one would burn for four hours.

That evening there was a power failure and the lights went off. I had a test on the next day. It was, therefore, indeed lucky that I had bought the candles.

I lit both the candles and resumed my studies. After few hours the power supply was restored, and I put out the candles. Upon checking the lengths of the burned candles, I found that the fat candle was now four times the length of the slender one. So, can you help me determine how long the candles had burned? Or, to put it differently, can you tell me for how long did the power failure last? Let's assume that the grocer was true to his word, and the maximum burn times of the fat and slim candles were indeed five hours and four hours respectively.

• Union Public Service Commission - www.upsc.gov.in
• IIT-Kharagpur - www.iitkgp.ac.in
• Indian Statistical Institute - www.isical.ac.in
• Indian Institute of Technology Madras - www.iitm.ac.in
• Indian Institute of Management, Ahmedabad - www.iimahd.ernet.in
• Indian Institute of Mass Commission - www.iimc.nic.in
• IIT Bombay - www.iitb.ac.in