Set up a ratio in each of  Problems. If the ratio cannot be reduced to an equivalent ratio in terms of small integers, then express it as a ratio of decimal equivalents with the smallest term set at 1. Maintain three-figure accuracy.

An online catalogue business sent out 12,000 emails to previous customers in its database, of which 10,500 were successfully delivered and 750 were opened. What is the ratio of emails sent to emails delivered to emails opened?