question_answer 1)

                A school has 8 periods a day each of 45 minutes duration. How long would each period be, if the school has 9 periods a day assuming the number of school hours to be the same?

Answer:

                Let each period be x minutes long. We have the following table                

Number of periods	8	9
Length of each period (in minutes)	45	\[x\]

  We note that more the number of periods, lesser would be the length of each period. Therefore, this is case of inverse proportion. So,           \[8\times 45=9\times x\] \[\Rightarrow \]               \[x=\frac{8\times 45}{9}\] \[\Rightarrow \]               \[x=40\]                 Hence, each period would be 40 minutes long.