From 1912 to 1928, the contact number for measles in the U. S. was 12.8. If we assume that Ro is still 12.8 and that inoculation is 100% effective -- everyone inoculated obtains immunity from the disease -- what fraction of the population must be inoculated to prevent an epidemic?

70-85%

Explanation:

Inoculation is basically developing herd immunity in a given population so that there is no more spread of the virus and the pandemic is prevented.

It is generally believed that if 75-80% people are inoculated then epidemic can be prevented.

answer; i believe the correct answer is (crops);

giant impact theory - the moon was formed from the collision between earth and another mars-sized body.

colliding planetesimals hypothesis - the moon was formed from the same cloud of material as earth.

capture hypothesis - the moon was locked into orbit by earths gravity as it was passing by it.

accretion hypothesis - the moon was formed from collisions and combining of planetesimals.

i think this is right, if not and you know better let me know.