A person running an 800-meter race averages 130 meters per minute for the first half of the race. The average speed for the remainder of the race is 145 meters per minute. What is the person's average speed for the entire 800 meters rounded to the nearest whole number?

Let, the speed of the train during returning journey be x kmph 

Speed during onward journey=  $(x+ 25\% of x)=\left(x+ \frac{25x}{100}\right)=\frac{5x}{4}$ kmph 

Distance covered in onward journey = $\frac{800}{2}=400 km$

Time taken by the train on onward journey= $\frac{{\displaystyle \frac{400}{5x}}}{4}$ hours [As, time= Distance/Speed]

And time by the train in returning journey = $\frac{400}{x}$ hours

According to the question,

$$\begin{gathered} \frac{{\displaystyle \frac{400}{5x}}}{4}+\frac{400}{x} =16 \\ \Rightarrow \left(\frac{400}{1}\times \frac{4}{5x}\right)+\frac{400}{x}=16 \\ \Rightarrow \frac{320}{x}+\frac{400}{x}=16 \\ \Rightarrow \frac{320+400}{x}=16 \\ \Rightarrow 16x=720 \\ \therefore x=45 kmph \end{gathered}$$

Speed of the train in the onward journey=$\frac{5x}{4}=\frac{5\times 45}{4}=56.25$ kmph 

মোট সময় নেয় ৩ ঘণ্টা

যাত্রা বিরতি ১ ঘণ্টা

নিট সময় নেয় = ৭ - ১ = ৬ ঘণ্টা

মোট দূরত্ব = ৩৩০ কি.মি

∴ গড় গতিবেগ $\frac{৩৩০}{৬}$ কি.মি/ ঘণ্টা = ৫৫ কি.মি / ঘণ্টা