Posted by Angela on Sunday, December 4, 2011 at 5:10pm.
Jack usually mowes his lawn in 7 hours. Marilyn can mow the same yard in 4 hours. How musch time would it take for them to mow the lawn together?

math/117  smiley face, Sunday, December 4, 2011 at 5:14pm
3 hrs

math/117  Damon, Sunday, December 4, 2011 at 5:15pm
jack mows (1/7) lawn per hour
marilyn mows (1/4) yard per hour
together they mow 1/7 + 1/4 yard per hour
= 4/28 + 7/28 = 11/28 yards per hour
so
28/11 = about 2.54 hours/yard

math/117  Angela, Sunday, December 4, 2011 at 5:17pm
Which one is the answer? 3 or 2.54?

math/117  Ms. Sue, Sunday, December 4, 2011 at 5:18pm
Damon's answer is correct.
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