the temperature at 12 noon was 10°C above zero. If it decreases at the rate of 2°C per hour until midnight, at what time would be

2 thoughts on “the temperature at 12 noon was 10°C above zero. If it decreases at the rate of 2°C per hour until midnight, at what time would be”

1. Correct option is

   B

   −14

   o

   C

   At 12 noon, the temperature =10°C above zero

   The temperature is decreasing at 2°C per hour

   8°C below zero =−8°C

   So, total fall in temperature from 10°C to 0°C and from 0°C to −8°C=18°C

   Since the temperature falls 2°C in every one hour.

   Therefore, to decrease 18°C, time taken = 18/2

   = 9 hours

   Present time is 12 noon so, the time when the temperature is −8°C

   =12noon+9hours

   So, The time at which the temperature will be −8°C=9PM

   At 9 PM, the temperature is −8°C, the temperature at 12 midnight will be =

   (−8°C)+(−2°C×3hours)

   =(−8°C)+(−6°C)

   =−14°C

   So, at 12 midnight the temperature will be−14°C.

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2. Answer:

   The temperature at 12 noon was 10°C

   and the temperature decreases at the rate of 2°C per hour until midnight

   so, for every hour the temperature is decreasing by 2°C

   So, at 1 pm, the temperature would be 10°C – 2°C = 8°C

   At 2 pm, the temperature would be 8°C – 2°C = 6°C

   At 3 pm, the temperature would be 6°C – 2°C = 4°C

   At 4 pm, the temperature would be 4°C – 2°C = 2°C

   At 5 pm, the temperature would be 2°C – 2°C = 0°C

   At 6 pm, the temperature would be 0°C – 2°C = -2°C

   At 7 pm, the temperature would be -2°C – 2°C = -4°C

   At 8 pm, the temperature would be -4°C – 2°C = -6°C

   At 9 pm, the temperature would be -6°C – 2°C = -8°C

   At 10 pm, the temperature would be -8°C – 2°C = -10°C

   At 11 pm, the temperature would be -10°C – 2°C = -12°C

   At 12 midnight, the temperature would be -12°C – 2°C = -14°C

   Hence the temperature would be 8°C below zero at 9 pm, and

   the temperature at midnight will be 14°C below zero.

   Step-by-step explanation:

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