$(30\times 4)\div (6-0.5)=120\div 5.5=\frac {240}{11}=21\frac 9{11}$ minutes. 
It is $4:00$ now. How many minutes does it take for the clock\textquotesingle s hour and minute hands to overlap for the first time? 

- $43\frac 7{11}$ minutes 
- $10\frac {10}{11}$ minutes 
- $21\frac 9{11}$ minutes 
- $22\frac 9{11}$ minutes 
- $42\frac 7{11}$ minutes 