Um motor elétrico recebe 2.800 kJ de energia elétrica. Transforma 900 kJ em energia térmica, 150.000 J em energia sonora e o restante em energia cinética. Podemos afirmar que seu rendimento é de: * a) 62,5 %
b) 68,7 %
c) 70,4 %
d) 72,7 %
e) 92,3 %

The circumference of a redwood tree trunk is 20π ft, and it is 100 ft tall. what is the approximate volume of the redwood tree trunk? 1,000π ft3 10,000π ft3 4,000π ft3 40,000π ft3

The management of a supermarket wants to adopt a new promotional policy of giving a free gift to every customer who spends more than a certain amount per visit at this supermarket. the expectation of the management is that after this promotional policy is advertised, the expenditures for all customers at this supermarket will be normally distributed with a mean of $95 and a standard deviation of $20. if the management wants to give free gifts to at most 10% of the customers, what should the amount be above which a customer would receive a free gift?

(60 points) explain this in detail