Problems

[Annie9]

http://www.majortests.com/gre/testpics/p001-9.gif

1. Amy has to visit towns B and C in any order. The roads connecting these towns with her home are shown on the diagram. How many different routes can she take starting from A and returning to A, going through both B and C and not travelling any road twice on the same trip?

A. 10

B. 8

C. 6

D. 4

E. 2

 

Ans : B

 

2. A cubical block of metal weighs 6 pounds. How much will another cube of the same metal weigh if its sides are twice as long?

A. 48

B. 32

C. 24

D. 18

E. 12

 

Ans: A

 

3. A straight fence is to be constructed from posts 6 inches wide and separated by lengths of chain 5 feet long. If a certain fence begins and ends with a post, which of the following could not be the length of the fence in feet? (12 inches = 1 foot)

A. 17

B. 28

C. 35

D. 39

E. 50

 

Ans: C

 

can you explain?:(

thnks

Annie

[ahtidevin]

1.just mark the arcs and trace the paths systematically,,i cud not think of any other way

 

2.it's a question of direct variation

if x be the side of the cube,

a volume of x^3 weighs 6 pounds

so (2x)^3=8x^3 weighs 8 times as much as the previous cube =8*6=48

 

3.Since it starts and ends with posts,number of posts always one greater than number of chains.Consider there are x chains so there are x+1 posts

 

total length will be of form

 

5x+(x+1)/2

=(11x+1)/2

 

now look at the answers and see if they satisfy this form

 

twice the answer must be a multiple of 11 plus 1

 

A.17*2=11*3+1

B.28*2=11*5+1

D.39*2=11*7+1

E.50*2=11*9+1

 

only c does not satisfy this format

[Mystery Man]

Good explaination for Ans 3.

Thanks!

[eddycurrent]

for question one...if you want to go from a to c...there are 2 paths...from c to b there are 2 paths and from b to a there is one path...also vice versa therefore 2*2*2=8 :)