Amodel of the ocean floor takes up 2/5 of the space in an aquarium. if 3/8 of the model is coral, what fraction of the space in the aquarium is taken up by coral?

Ineed with number 6 , explain how to get 1978

Aparticular telephone number is used to receive both voice calls and fax messages. suppose that 25% of the incoming calls involve fax messages, and consider a sample of 25 incoming calls. (a) what is the expected number of calls among the 25 that involve a fax message?

1) prove that 731^3−631^3 is divisible by 100 2) prove that 99^3−74^3 is divisible by 25