The answer would be about 66. Ps . I hate that website. It's for common core learingl it is soooo boring !
So...the diameter is increasing at a rate if 2cm/minute, therefore the radius (1/2 the diameter) is increasing at half the rate. You will learn how to calculate the rate of change at a specific point in time in calculus.
Answer:
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He swam 1,800 laps total in 12 weeks. Each week, he swam 150 laps because 1800/2=150 in 5 days. Each day, he swam 30 laps because 150/5=30, in 45 minutes. His average time was 30/45=2/3 At that rate, in one hour, he would swim 2/3*60 = 2/3 x 60 = 40 laps/hour Final answer is 40