GMAT Problem Solving Discussions

[Inder.14]

Originally Posted by msd_2008 (GMAT Problem Solving Discussions)
Hello,

Someone please help me with the following question:

Q.1 A circular jogging track forms the edge of a circular lake that has a diameter of 2 miles. Johanna walked once around the track at the average speed of 3 miles per hour. If t represents the number of hours it took Johanna to walk completely around the lake, which of the following is a correct statement?

A. 0.5< t < 0.75
B. 1.75< t < 2.0
C. 2.0 < t < 2.5
D. 2.5 < t < 3.0
E. 3 < t < 3.5

Thanks
MSD

Originally Posted by ashishjha100

i think ans is C........if it is correct i'll give reasoning.....

i guess the correct answer should be D.msd_2008 ,can you please verify

[jpmadhav]

Hi Bhavin,

I guess i made some mistake in approach towards the answer...Rather i took it as Square than Rhombus.....

Explanation goes like this....

ABCD is a Rhombus....

AB=BC=CD ...also =AD....

so AB=BC=CD=AD=r

Take centre of BD as O....

and by Rhombus properties ...AO=OC = AC/2 = r/2 ..
and AOB=COB ...is right angle

so by Pythagoras theorem ...AB^2 = AO^2 + OB^2....
==> r^2 = (r/2)^2 + OB^2...

so OB = root(3)/3....

so tan (x) = AO/OB....(r/2)/(root(3)*r)/2 = 1/root(3)
==> x = tan Inverse (1/root(3)) = 30 degrees....

Correct me if i am wrong...

[abhishekag05]

Originally Posted by Inder.14

Originally Posted by msd_2008 (GMAT Problem Solving Discussions)
Hello,

Someone please help me with the following question:

Q.1 A circular jogging track forms the edge of a circular lake that has a diameter of 2 miles. Johanna walked once around the track at the average speed of 3 miles per hour. If t represents the number of hours it took Johanna to walk completely around the lake, which of the following is a correct statement?

A. 0.5< t < 0.75
B. 1.75< t < 2.0
C. 2.0 < t < 2.5
D. 2.5 < t < 3.0
E. 3 < t < 3.5

Thanks
MSD



i guess the correct answer should be D.msd_2008 ,can you please verify

Distance travelled by Johanna = 3t miles = Circumfrence of lake = 2//r
so 3t = 22/7*2
or t = 2.095
So correct answer is choice C

[ashishjha100]

A merchant paid $300 for a shipment of x identical calculators. The merchant used 2 of the calculators as demonstrators and sold each of the others for $5 more than the average (arithmetic mean) cost of the x calculators. If the total revenue from the sale of the calculators was $120 more than the cost of the shipment, how many calculators were in the shipment?
(A) 24
(B) 25
(C) 26
(D) 28
(E) 30

Pl help.....

[Dopa]

Originally Posted by ashishjha100

A merchant paid $300 for a shipment of x identical calculators. The merchant used 2 of the calculators as demonstrators and sold each of the others for $5 more than the average (arithmetic mean) cost of the x calculators. If the total revenue from the sale of the calculators was $120 more than the cost of the shipment, how many calculators were in the shipment?
(A) 24
(B) 25
(C) 26
(D) 28
(E) 30

Pl help.....

@ashishjha100 -
I hope this will help -

Avg (Arithmetic mean) cost for x calculators = 300/x
Selling price for 1 calculator = (300/x) + 5 (5 more than avg price of calculator)
No. of calculators sold by merchant = x-2 (2 less than no. of calculators bought)
Total revenue from the sale = 300 + 120 = 420

we know that - Total revenue = Selling price for 1 calculator * No. of calculators sold
=> [(300/x) + 5] * [x-2] = 420
After simplifying quadratic equation, you'll get 30 as the answer. Also, you can try putting 30 directly in the above equation.

P.S - I read somewhere that when you need to chose and eliminate the choices, start from E to A.

[reddy.harikisho]

Originally Posted by ashishjha100

A merchant paid $300 for a shipment of x identical calculators. The merchant used 2 of the calculators as demonstrators and sold each of the others for $5 more than the average (arithmetic mean) cost of the x calculators. If the total revenue from the sale of the calculators was $120 more than the cost of the shipment, how many calculators were in the shipment?
(A) 24
(B) 25
(C) 26
(D) 28
(E) 30

Pl help.....

avg for x calculators is 300/x.
he sold (x-2) calculators for (300/x+5).
so revenue (x-2)(300/x+5) = 300+20.

it is easy to solve it by substitution rather than solving the equation. one can save some time by substituting lowest and highest (here 24 and 30) and then moving on to next options. after doing with highest and lowest you kind of get the idea which value it could be. this just saves some seconds of your time.

[ashishjha100]

Originally Posted by Dopa

@ashishjha100 -
I hope this will help -

Avg (Arithmetic mean) cost for x calculators = 300/x
Selling price for 1 calculator = (300/x) + 5 (5 more than avg price of calculator)
No. of calculators sold by merchant = x-2 (2 less than no. of calculators bought)
Total revenue from the sale = 300 + 120 = 420

we know that - Total revenue = Selling price for 1 calculator * No. of calculators sold
=> [(300/x) + 5] * [x-2] = 420
After simplifying quadratic equation, you'll get 30 as the answer. Also, you can try putting 30 directly in the above equation.

P.S - I read somewhere that when you need to chose and eliminate the choices, start from E to A.

Thanks Dopa,
I was in a confusion to take 300 as cargo charge or total price of x calculators......

[Inder.14]

Ya buddy got it........Some calculation mistake .........
thanks a lot for explaining

Originally Posted by Inder.14 (GMAT Problem Solving Discussions)
Originally Posted by msd_2008 (GMAT Problem Solving Discussions)(GMAT Problem Solving Discussions)
Hello,

Someone please help me with the following question:

Q.1 A circular jogging track forms the edge of a circular lake that has a diameter of 2 miles. Johanna walked once around the track at the average speed of 3 miles per hour. If t represents the number of hours it took Johanna to walk completely around the lake, which of the following is a correct statement?

A. 0.5< t < 0.75
B. 1.75< t < 2.0
C. 2.0 < t < 2.5
D. 2.5 < t < 3.0
E. 3 < t < 3.5

Thanks
MSD



i guess the correct answer should be D.msd_2008 ,can you please verify

Originally Posted by abhishekag05

Distance travelled by Johanna = 3t miles = Circumfrence of lake = 2//r
so 3t = 22/7*2
or t = 2.095
So correct answer is choice C

[msd_2008]

Originally Posted by Inder.14

Originally Posted by msd_2008 (GMAT Problem Solving Discussions)
Hello,

Someone please help me with the following question:

Q.1 A circular jogging track forms the edge of a circular lake that has a diameter of 2 miles. Johanna walked once around the track at the average speed of 3 miles per hour. If t represents the number of hours it took Johanna to walk completely around the lake, which of the following is a correct statement?

A. 0.5< t < 0.75
B. 1.75< t < 2.0
C. 2.0 < t < 2.5
D. 2.5 < t < 3.0
E. 3 < t < 3.5

Thanks
MSD



i guess the correct answer should be D.msd_2008 ,can you please verify

The correct answer is C.

[msd_2008]

Need help with the following problem :

Q. How many 5 digit numbers can be formed which are divisible by 3 using the numerals 0,1,2,3,4,5 (WITHOUT REPETITION)
a. 216
b. 3152
c. 240
d. 600

Rgds
MSD