roll the log

[bhumika.k.shah]

A log with a radius of 2.5 feet is rolled up a hill. If it takes 30 seconds to roll the log one complete revolution, approximately how many minutes will it take to roll the log 75 yards? [3 feet = 1 yard]

A 2
B.3
C.5
D.7
E.9

[thephoenix]

IMO D

radius=2.5 ft
circumference=2 pir r=5 pie ft=5 pie/3 yards

time taken for 5 pie/3 yards=30sec=1/2 min
for 75 yards=(1/2)*(3/5 pie)*75=45*7/44=1.02*7=aprrox 7
oa pls

[ajith]

A log with a radius of 2.5 feet is rolled up a hill. If it takes 30 seconds to roll the log one complete revolution, approximately how many minutes will it take to roll the log 75 yards? [3 feet = 1 yard]

A 2
B.3
C.5
D.7
E.9

Perimeter of the circle with radius 5/2 = 2*pi*5/2 = 5pi

The distance log rolls in 30 seconds = 5pi

Distance log rolls in one sec = 5pi/30 feet

Time taken to roll 225 feet = 225*30/5pi seconds
= 225/10*pi minutes
= 7.16 minutes

Hence D

[bhumika.k.shah]

how can u solve such sums at ease???

For a person like me , though i got the correct answer, this took a while!
Conversions and blah if slightly mistaken can get me a wrong answer!

wish math was so easy for everyone + GMAT verbal easy for me

A log with a radius of 2.5 feet is rolled up a hill. If it takes 30 seconds to roll the log one complete revolution, approximately how many minutes will it take to roll the log 75 yards? [3 feet = 1 yard]

A 2
B.3
C.5
D.7
E.9

Perimeter of the circle with radius 5/2 = 2*pi*5/2 = 5pi

The distance log rolls in 30 seconds = 5pi

Distance log rolls in one sec = 5pi/30 feet

Time taken to roll 225 feet = 225*30/5pi seconds
= 225/10*pi minutes
= 7.16 minutes

Hence D

[ajith]

how can u solve such sums at ease???

For a person like me , though i got the correct answer, this took a while!
Conversions and blah if slightly mistaken can get me a wrong answer!

wish math was so easy for everyone + GMAT verbal easy for me

Well, I will tell u my case, I have been studying maths for I do not know how long

Engg, MBA ...

I still can't understand why verbal is so tough for me

[bhumika.k.shah]

Me not from an engineering background so i am sure u have an idea how difficult this would be for me!
besides i am sure all my posts wud have made you realise that!

coz i insist on asking for detailed step wise explanations!

As for verbal - CR and RC are like blood sucking insects to me! :'(

how can u solve such sums at ease???

For a person like me , though i got the correct answer, this took a while!
Conversions and blah if slightly mistaken can get me a wrong answer!

wish math was so easy for everyone + GMAT verbal easy for me

Well, I will tell u my case, I have been studying maths for I do not know how long

Engg, MBA ...

I still can't understand why verbal is so tough for me