The price of a dress was first discounted by a certain percent and later by 25 percent of the discounted price. If these two discounts are equivalent to a single discount of 40% of the original price, what was the first discount?
A. 10%
B. 15%
C. 20%
D. 30%
E. 65%
The rear wheels of a car crossed a certain line 0.5 second after the front wheels crossed the same line. If the centers of the front and rear wheels are 20 feet apart and the car traveled in a straight line at a constant speed, which of the following gives the speed of the car in miles per hour?
A. (20/5.280)(60^2/0.5)
B. (20/5.280)(60/0.5)
C.(20/5.280)(0.5/60^2)
D. (20)(5.280) / (60^2)(0.5)
E. (20)(5.280) / (60)(0.5)
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jayhawk2001
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Let x be the first discount.jamesk486 wrote:The price of a dress was first discounted by a certain percent and later by 25 percent of the discounted price. If these two discounts are equivalent to a single discount of 40% of the original price, what was the first discount?
A. 10%
B. 15%
C. 20%
D. 30%
E. 65%
(1-x)(.75) = 0.6
Solving for x, we get 0.2 i.e. 20%
I guess we need the conversion factor between feet and miles tojamesk486 wrote: The rear wheels of a car crossed a certain line 0.5 second after the front wheels crossed the same line. If the centers of the front and rear wheels are 20 feet apart and the car traveled in a straight line at a constant speed, which of the following gives the speed of the car in miles per hour?
A. (20/5.280)(60^2/0.5)
B. (20/5.280)(60/0.5)
C.(20/5.280)(0.5/60^2)
D. (20)(5.280) / (60^2)(0.5)
E. (20)(5.280) / (60)(0.5)
answer this.
0.5 * speed = 20 feet
0.5 / (60*60) * speed = 20 feet (convert sec to hour)
speed = (20 * 60 * 60 / 0.5) feet/hr
speed = (20 * 60 * 60) / (0.5 * 5280) miles/hr
I'm not too sure if GMAT expects you to remember conversion
factors from feet to miles.
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Cybermusings
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The rear wheels of a car crossed a certain line 0.5 second after the front wheels crossed the same line. If the centers of the front and rear wheels are 20 feet apart and the car traveled in a straight line at a constant speed, which of the following gives the speed of the car in miles per hour?
A. (20/5.280)(60^2/0.5)
B. (20/5.280)(60/0.5)
C.(20/5.280)(0.5/60^2)
D. (20)(5.280) / (60^2)(0.5)
E. (20)(5.280) / (60)(0.5)
20 feet is the distance which is covered in .5 seconds...
20 ft = 20/5280 miles
.5 sec = .5/60*60 hrs
Speed = Distance/Time
= (20/5280) / [.5/3600]
= (20/5280)*3600/.5
So option A
A. (20/5.280)(60^2/0.5)
B. (20/5.280)(60/0.5)
C.(20/5.280)(0.5/60^2)
D. (20)(5.280) / (60^2)(0.5)
E. (20)(5.280) / (60)(0.5)
20 feet is the distance which is covered in .5 seconds...
20 ft = 20/5280 miles
.5 sec = .5/60*60 hrs
Speed = Distance/Time
= (20/5280) / [.5/3600]
= (20/5280)*3600/.5
So option A
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mmslf75
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jamesk486 wrote:The price of a dress was first discounted by a certain percent and later by 25 percent of the discounted price. If these two discounts are equivalent to a single discount of 40% of the original price, what was the first discount?
A. 10%
B. 15%
C. 20%
D. 30%
E. 65%
I have yet another method to this...
When you have two such percentages acting one after the other..
a + b + (ab/100) = Effective Percentage
a - 25 + a (-25/100) = -40
a - 25 - (a/4) = -40
3a = - 160 + 100
a = -20 => Discount of 20 percent
