4. Not all metals are magnetic. Metals that are magnetic, like iron, are called ferromagnetic. True or false? a. True; only some metals have electrons that spin in the same direction
b. False; all metals have electrons that spin in the same direction
c. True; only some metals have electrons that spin in opposite directions
d. False; all metals are magnetic

The temperature in gavin's oven is a sinusoidal function of time. gavin sets his oven so that it has a maximum temperature of 280°f and a minimum temperature of 240°. once the temperature hits 280°, it takes 20 minutes before it is 280° again. gavin's cake needs to be in the oven for 30 minutes at temperatures at or above 270°. he puts the cake into the oven when it is at 260° and rising. how long will gavin need to leave the cake in the oven? (round your answer to the nearest minute.)