Neha has a watch which gains 2 % per hour whe | vedclass

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(D) The temperature starts at $32^{\circ}C$ at $8$ $a.m.$ and rises at $2^{\circ}C/h$ until $4$ $p.m.$ ($8$ hours later). At $4$ $p.m.$,the temperatur

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$	ext{None of these}$

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(D) The temperature starts at $32^{\circ}C$ at $8$ $a.m.$ and rises at $2^{\circ}C/h$ until $4$ $p.m.$ ($8$ hours later). At $4$ $p.m.$,the temperature is $32 + (8 	imes 2) = 48^{\circ}C$. From $8$ $a.m.$ to $12$ $p.m.$ ($4$ hours),the temperature rises from $32^{\circ}C$ to $40^{\circ}C$. From $12$ $p.m.$ to $4$ $p.m.$ ($4$ hours),the temperature is in the range $40^{\circ}C - 48^{\circ}C$,so the watch gains $2\%$ per hour. Gain per hour = $0.02 	imes 3600 	ext{ seconds} = 72 	ext{ seconds}$. Total gain from $12$ $p.m.$ to $4$ $p.m.$ = $4 	imes 72 = 288 	ext{ seconds}$. After $4$ $p.m.$,the temperature falls at $2^{\circ}C/h$. From $4$ $p.m.$ to $7$ $p.m.$ ($3$ hours),the temperature falls from $48^{\circ}C$ to $42^{\circ}C$. Since the temperature remains above $40^{\circ}C$ during this interval,the watch continues to gain $2\%$ per hour. Gain from $4$ $p.m.$ to $7$ $p.m.$ = $3 	imes 72 = 216 	ext{ seconds}$. Total gain = $288 + 216 = 504 	ext{ seconds} = 8 	ext{ minutes } 24 	ext{ seconds}$. Thus,the watch shows $7:08:24$ $p.m.$

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