The cost of each adult's ticket for a certain concert was $3

nbr of adult tickets=a
nbr of children tickets=c
average=(30a+24c)/a+c

S1 says c=2a

average= 30a+24*2a/3a
=78a/3a
=26

suff

s2 is insuff since we dont know relation between a and c.
hence A.

From the question stem we know that

Adult Ticket = $30 (A)
Childrens Ticket =$24 (C)

From 1. we know that A= x AND C = 2x so we can test.
If there were x = 1 then the average ticket price is $26.

1(36) + 2(24) = 78 and 78 divided by 3 tickets is $26

If x = 2 the average ticket price is also #26.

2(36) + 4(24) = 156 and 156 divided by 6 tickets is $36

SUFF

2. Does not give any information that would help solve this question INSUFF

MY ANSWER IS A

thanks for the answer...i am convinced abt the answer...
its A

hey champs... the OA: is A
still it looks like if hannah purchased 4 child tickets only, than the avg would of been the price of the ticket...
so b would of been sufficient...
but OA says A

You would be assuming that she purchased no adult's ticket if statement 2 were to be sufficient. But it is not given that she purchased no adult tickets or 'only children's tickets'. You cannot assume this is DS questions. Statement 2 only tells you how many children's tickets she purchased. It gives you incomplete information.

Statement 1 alone is sufficient since it tells you the ratio of the number of adult's tickets and children's tickets. With this ratio, you can easily find the average.
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Karishma, but doesn't it also mean assuming otherwise - that tickets for both categories were purchased definitely. It is not given in the question stem that tickets for both categories (Adult and Children) were purchased. Statement 2, in my view, should also be self sufficient to answer the question (keeping no assumptions in mind).

You are absolutely not assuming that she must have purchased tickets of both types.

The question is: What is the average price of the tickets she purchased.

What you know from stmnt 2: She purchased 4 children's tickets

How will you answer?
You will say that if she purchased no adult tickets, the average price is $24. If she did purchase adult's tickets too, the avg price is higher. Did you get a definitive unique value for the average price? No. This means this statement is not sufficient alone.

This sufficiency condition is the basic concept of DS questions which you must understand very properly to do well in DS.
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Statement 1:
No of Adult tickets = A
No of children's tickets = 2A

Total cost of tickets = A*30 + 2A*24
Mean = Total/3A = (A*30 + 2A*24)/3A, cancel A from numerator and denominator.

Statement 2:
No info on number of Adult's tickets. Insufficient.

Hence A.

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