to mow the lawn with the help of two people
2007-09-23 11:42:15 · 10 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
30+45= 1hour 15mins
Johns got to wait till his brother is finished.
I think???
2007-09-24 01:17:52 · answer #1 · answered by jayr 3 · 0⤊ 1⤋
"You can mow your whole lawn in 45 minutes" You mow 1/45 of the lawn per minute. "your neighbor can mow your whole lawn in 30 minutes" neighbor mows 1/30 of the lawn per minute How long would it take to mow the lawn together? Together, you mow 1/45 + 1/30 = 1/18 of the lawn per minute. time = 1 lawn × 1 minute/(1/18 lawn) = 18 minutes It takes 18 minutes for the two of you to mow the lawn. Check: 18 minutes × (1/45) lawn/minute = 2/5 lawn You mow 2/5 of the lawn in 18 minutes. 18 minutes × (1/30) lawn/minute = 3/5 lawn neighbor mows 3/5 of the lawn in 18 minutes 2/5 lawn + 3/5 lawn = 1 lawn
2016-05-17 06:19:48 · answer #2 · answered by ? 3 · 0⤊ 0⤋
Depends how fast the two people helping him can mow the lawn.
2007-09-23 11:46:11 · answer #3 · answered by Andrew 4 · 0⤊ 0⤋
Assume question is asking how long will it take two of them working together.
Let area of lawn = X m ²
John`s rate of work = X / 45
Brother`s rate of work = X / 30
Combined rate = X / 45 + X / 30
Combined rate = 2X / 90 + 3X / 90 = 5X / 90
Time taken = t mins, say
t = X / ( 5X / 90 ) mins
t = 90 / 5 mins
t = 18 mins
Will take 18 mins. when working together.
2007-09-24 21:29:51 · answer #4 · answered by Como 7 · 2⤊ 0⤋
45 minutes.
Because they've only got one lawn mower between the three of them.
(John must have a bigger garden than his brother.)
2007-09-23 11:46:38 · answer #5 · answered by caldini 3 · 1⤊ 0⤋
45 minutes..it says right in the question it takes 45 minutes...and it doesnt say anything about more mowers...
whats his brother have to do with it?
2007-09-23 11:51:28 · answer #6 · answered by briski_2005 1 · 0⤊ 0⤋
pointless question - but hey 2 points
2007-09-23 11:52:31 · answer #7 · answered by Anonymous · 0⤊ 0⤋
its already been done twice...tell john to have a beer and go and watch the cricket
2007-09-23 11:46:02 · answer #8 · answered by jani_g 3 · 3⤊ 0⤋
not so clear
2007-09-23 11:46:25 · answer #9 · answered by CPUcate 6 · 0⤊ 0⤋
Please be clear about the question.
2007-09-23 12:01:44 · answer #10 · answered by mr_maths_man 3 · 0⤊ 1⤋