<p>Hey,
can anyone give me a clear explanation on how to answer this problem?
The temperature at 6 am on a certain day was 11 degrees Celsius. It increased at a constant rate until 3 pm. It then decreased at the same constant rate until 9pm. if the temperature at 9 pm is 17 degrees Celsius. what was the temperature at 2 pm that day?
thanks.</p>
<p>There are 9 hours between 6AM and 3PM.</p>
<p>Let R be the rate of temperature increase (per hour) between 6AM and 3PM. So the temperature at 3PM is: 11 + 9*R.</p>
<p>There are 6 hours between 3PM and 9PM.</p>
<p>The rate of temperature decrease (per hour) between 3PM and 9PM is -R. So the temperature at 9PM is: Temperature-at-3PM - 6<em>R. We know the temperature at 3PM in terms of R. So we have that the temperature at 9PM is: 11 + 3</em>R. We’re told that this is 17. So solving for R we get R = 2.</p>
<p>Now go back to the temperature between 6AM and 3PM. The temperature at 3PM is 11 + 18 or 29. (We get this by plugging in R=2 in 11 + 9*R above). The temperature at 2PM is 2 degrees less than at 3PM, or 27 degrees.</p>
<p>It may help you to plot this as a graph. On the y-axis plot the temperature, and on the x-axis plot the time.</p>