unrelated to part above problem$)$ A store manager has a promise that if there are more than three customers waiting for service at anytime, he himself will open a line to serve the customers. Customer arrives on an average $5$ minutes apart. One regular person at the service desk serves $30$ customers per hour. What percentage of time manager will have to help service desk clerk to keep the stores service promise? $12/$hour $(5$ minutes $---60/5=12/$hour$)30/$hour