



 
Hi Sara. I'll show you how to do (a) and you will see how to do (b). The time to drain the tank will be smallest when the amount of water is smallest and the drainage rate is highest. So what is the highest drainage rate? Since the rate is rounded to the nearest 0.5 liter per minute, it could be as much as 8.25 liters per minute. What is the smallest amount of water? It is the smallest volume cuboid, which means the cuboid with the smallest dimensions. Since the dimensions are rounded to the nearest 0.1 meters, the smallest cuboid would be 1.55 by 1.15 by 0.75, so the volume is 1.55 x 1.15 x 0.75 x 1000 liters per cubic meter, which is 1336.875 liters. Drained at a rate of 8.25 liters per minute, that takes 1336.875/8.25 = 162.05 minutes. Cheers,  


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