Answer:
Central bank of any country often intervenes when the matter of currency exchange rates is hot.
Now in order to remain competitive and make the exports cheaper so that the quantity of exports increase, the Central bank of China would intervene and deliberately decrease the value of Chinese Yuan by increasing the supply of Yuan in the market and purchasing the dollar in big amount to store it, hence increasing the demand of dollar and ultimately increasing its value.
This all can be done through the Open Market Operations.
Thank You, Hope this helps.
