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These ones either I got them wrong or guessed and got them right.
Q1:
Average (arithmetic mean) of Test Scores in Class R
Average scores for the boys 90
Average scores for the girls 81
Average scores for the class 84
What is greater? The number of boys in the class who took the test or
The number of girls in the class who took the test.
A1: the number of girls took the test is greater.
I got so confused on this... Some tips will be welcome
Q2:
x > 1
y > 1
What is greater? 1 / ( 1/x + 1/y) or 1/x + 1/y that is...
a. b.
1 1 1
------------------- or ------- + ------
1 1 x y
------- + ------
x y
A2: Need more information to determine the relationship.
I got this one wrong after plugging in x = 2, y = 3
so i figured....
a. xy b. y + x
---------- ----------
x + y xy
6/5 > 5/6
or if x= 2, y = 5
then
10/7 > 7/10
or if x = 5, y = 5
then 25/10 > 10/25
I can't get why you need more info to determine the relantionship..
What's the trick here?
Lastly,
Q3: today is jack's 12th birthday and His father's 40th birthday. How
many years from today will Jack's father be twice as old as Jack is at
the time?
a. 12 b.14 c. 16 d.18 e. 20
A3: C.
INitially, I had set up an equation like this.
After x years, jack's father's age is twice jack's, after x years Jack
will be
12 + x years old
and father is 2(12+x)
I think this is where I made a mistake in assuming
12 + x = 2 (12 + x )
This didn;t give the right answer. so I plugged in the choices into
jack's and father's age and see when father 's age is twice jack's.
Now thinking about it, what i needed was that fact that Father is 40
now.
ie. 40 + x = 2 ( 12 + x )
then 40 + x = 24 +2x
16 = x
ie. in 16 years.
Sometime the wording gets so bizzare, I make mistakes in setting up the
problem.
Any tips you guys use for problems like this?
Again, thanks for any info.
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