Question

One candle is 50cm high and
can burn for 3 hours. Another
one is 70cm high and can
burn for 6 hours. How long
does it take for this two
candles to reach the same
height?​

Answer 1

Thus, Time take for this two candles to reach the same height is $4\, hr$

Step-by-step explanation:

Given,

One candle is $50cm$ high and  can burn for $3hr$ another  one is $70cm$ high and can  burn for $6hr$

Speed of burning of first candle $=\frac{50}{3}$ cm/hr

Speed of burning of second candle$=\frac{70}{6}= \frac{35}{3}$ cm/hr

Let the new lengths after burning of first second candle be $x\,cm$

Let the time taken to burn be $t\,hr$

Distance traveled by the first candle will be $(50-x)cm$

And distance traveled by the second candle will be $(70-x)cm$

Now,

Distance = speed × time

∴ $(50-x)=\frac{50}{3}\times t$__1

And  $(70-x)=\frac{35}{3}\times t$__2

Substituting equation-2 & 1,

∴$(70-x-50+x)=\frac{35t}{3}-\frac{50t}{3}$

⇒$20\times 3=-15t$

∴$t=-4\,hr$

∴ Time take for this two candles to reach the same height is $4\, hr$

Answer 2

Answer:

6 hours

Step-by-step explanation: