Question

The temperature at 12 noon was 15c above zero
it decreases at the rate of 2c per hour until midnight
at what time ,would the temperature be 5c below 0c ? what would be the temperature at the midnight

Answer 1

Answer:

time will be 10

amd

temperature at midnight is -9degree c

Answer 2

$\large\bf\underline{Given:-}$

• The temperature at 12 noon was 15°C above zero.
• Temperature decreases at the rate of 2°C per hour until midnight.

$\large\bf\underline {To \: find:-}$

• The time when the temperature will be 5°C below zero.
• Temperature at midnight.

$\rule{300}{2}$

At 12 noon, the temperature = 15° C above zero

The temperature is decreasing at 2° C per hour

5° C below zero = - 5° C

So, total fall in temperature from 10° C to 0° C and from 0° C to - 5° C = 15° C

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

Therefore, to decrease 15° C, time taken = 15/2

= 7.5 hours

Present time is 12 noon so, the time when the temperature is - 5° C

= 12 noon + 7.5 hours

So, The time at which the temperature will be - 5° C = 7:30 PM

$\bigstar$At 7:30 PM, the temperature will be - 5° C

The temperature at 12 midnight will be = 

(- 5° C) + (- 2° C × 4.5 hours)

= (- 5° C) + (- 9° C)

= - 14° C

$\bigstar$At 12 midnight the temperature will be - 14°

$\rule{300}{2}$