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The following diagram shows the temperatures during a day :

(i) Plot the points on a graph and then join the points with straight lines.

(ii) Approximately when did the temperature first reach 30°C? Was the temperature increasing or decreasing at this time ?

(iii) For how long was the temperature above 40°C?

(iv) By how much did the temperature fall between 4 p.m. and 6 p.m.?

i) Take time as x axis and temperature as y axis, plot (5,21), (7,23), (9,29), (11,37), (13,40), (15,41), (17,36), (19,34), (21,32)

Since the time taken is mentioned question is in 12 hr format, we will plot the graph in 24 hr time format to avoid any confusion.

ii) The temperature will first reach 30 degrees at approx 9:15, there is 8 degree changes in temperature in 120 mins, so 1 degree will change in 15 mins.

iii) For about 2 hours, the temperature was above 40 degrees.

iv) The temperature at 4pm is (41+36)/2 = 38.5 degree and the temperature at 6 pm is (36+34)/2 = 35 degree, so there is 38.5-35 = 2.5 degree fall in the temperature between 4 pm and 6 pm.

Regards

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