Question: the speed of a railway engine is 63 km per hour when no compartment is attached , and the reduction in speed is directly proportional to the square root of the number of compartments attached . if the speed of the train carried by this engine is 24 km per hour when 9 compartments are attached , the maximum number of compartments that can be carried by the engine is :
A) 19
B) 18
C) 16
D) 17
E) 23
Correct answer: e
Grade: 7 | Topic: Ratios and proportions | Difficulty: Hard | Standard: 7.RP.A.2