Please help with these.
I guessed on both (I hope I can guess this well on the real test).
For the rate question, I get stuck when I need to figure out how much (% of) work is done by x if x& y are working together....
thanks
2 gmatprep questions
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Prob 1.
F =120, t =10 put these values in the given equation
F = 120 ( 2 ^ -at ) + 60
Solving this for the above values will give you, a = 1/10
now when t = 30, F = ?
put a = 1/10, t = 30 in F = 120 ( 2 ^ -at ) + 60
F = 75
Ans B
F =120, t =10 put these values in the given equation
F = 120 ( 2 ^ -at ) + 60
Solving this for the above values will give you, a = 1/10
now when t = 30, F = ?
put a = 1/10, t = 30 in F = 120 ( 2 ^ -at ) + 60
F = 75
Ans B
Prob 2.
First machine comepletes the task in 8 hrs so speed is 1/8.
Second machine comepletes the task in 8 hrs so speed is 1/4.
Both machines together will complete the task in 1/4 + 1/8 = 3/8.
So time required will be 8/3 = 2.66 Approx
Percent change = 2.66 - 1/ 1 * 100 = 166.66%
So both machines working together will work 66.66% faster
Ans D.
First machine comepletes the task in 8 hrs so speed is 1/8.
Second machine comepletes the task in 8 hrs so speed is 1/4.
Both machines together will complete the task in 1/4 + 1/8 = 3/8.
So time required will be 8/3 = 2.66 Approx
Percent change = 2.66 - 1/ 1 * 100 = 166.66%
So both machines working together will work 66.66% faster
Ans D.
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,
Can you explain the temperature question again please?
F = 120 ( 2 ^ -at ) + 60
Solving this for the above values will give you, a = 1/10
Can you break down how you solved for a?
Also, when I plugged 1/10 into the equation, I got 80, how did you get 75?
put a = 1/10, t = 30 in F = 120 ( 2 ^ -at ) + 60
F = 75
Thanks
Can you explain the temperature question again please?
F = 120 ( 2 ^ -at ) + 60
Solving this for the above values will give you, a = 1/10
Can you break down how you solved for a?
Also, when I plugged 1/10 into the equation, I got 80, how did you get 75?
put a = 1/10, t = 30 in F = 120 ( 2 ^ -at ) + 60
F = 75
Thanks
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- Master | Next Rank: 500 Posts
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Hi again,
for the first question, why did you use percent change to calculate the answer? and what do you get the 1 you're subtracting from 2.66?
for the first question, why did you use percent change to calculate the answer? and what do you get the 1 you're subtracting from 2.66?
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F = 120 (2^ -at ) + 60
We know that F is 120 and t =10 ...no forget all exponent rules
Just place the values
120 = 120 (2^ -a10 ) + 60
120 = 120 (1/2^a10 ) + 60
In order to get a 120 on LHS we need 60 + 60
What number will give us a 60 ..120/2 is 60 Hence the powers should cancel each other out
Hence a needs to be 1/10..
NOw if we put 1/30 in the equation
put a = 1/10, t = 30 in F = 120 ( 2 ^ -at ) + 60
F = 120 (1/2 ^1/10 *30) + 60
F = 120/8 + 60
= 15 + 60
= 75
We know that F is 120 and t =10 ...no forget all exponent rules
Just place the values
120 = 120 (2^ -a10 ) + 60
120 = 120 (1/2^a10 ) + 60
In order to get a 120 on LHS we need 60 + 60
What number will give us a 60 ..120/2 is 60 Hence the powers should cancel each other out
Hence a needs to be 1/10..
NOw if we put 1/30 in the equation
put a = 1/10, t = 30 in F = 120 ( 2 ^ -at ) + 60
F = 120 (1/2 ^1/10 *30) + 60
F = 120/8 + 60
= 15 + 60
= 75
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- Master | Next Rank: 500 Posts
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As for the second one ..just pick simple numbers
Say first machine takes 8 hrs
Second machine takes 4 hrs
Lets say k = 32
One machine takes 8 hrs to make 32 items so 4 items in one hour
Second takes 4 hrs to make 32 items so 8 items in one hour
So % = 8/12*100 = 66.66
Hope this helps
Say first machine takes 8 hrs
Second machine takes 4 hrs
Lets say k = 32
One machine takes 8 hrs to make 32 items so 4 items in one hour
Second takes 4 hrs to make 32 items so 8 items in one hour
So % = 8/12*100 = 66.66
Hope this helps