1. For each 1/2 hour, the frog climbs 2 cm
=> For each 1/4 (=0.25) hour, the frog climbs 1 cm
=> For each 2 hours, the frog climbs 8 cm
2. After 2 hours, the frog take rest 1/2 hour and slips by 1 cm
=> For 2.5 hours, the frogs climb 7cm
=> Needs less than \(2.5 * (\frac{28}{7}) = 10\) hours
At after 9.5 hours => the frog already climbs 29 cm (the last 1/2 hour of the 10-hour period is the frog slipping 1cm)
At after 9.25 hours => the frog be climbs 28 cm (since for each 1/4 (=0.25) hour, the frog climbs 1 cm)
=> 9.25 hours
Answer C
=> For each 1/4 (=0.25) hour, the frog climbs 1 cm
=> For each 2 hours, the frog climbs 8 cm
2. After 2 hours, the frog take rest 1/2 hour and slips by 1 cm
=> For 2.5 hours, the frogs climb 7cm
=> Needs less than \(2.5 * (\frac{28}{7}) = 10\) hours
At after 9.5 hours => the frog already climbs 29 cm (the last 1/2 hour of the 10-hour period is the frog slipping 1cm)
At after 9.25 hours => the frog be climbs 28 cm (since for each 1/4 (=0.25) hour, the frog climbs 1 cm)
=> 9.25 hours
Answer C
Statistics : Posted by Gemmie • on 31 Jul 2015, 03:10 • Replies 9 • Views 11903
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