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14 Nov 2014, 09:57
Kudos
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E
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
15%
(low)
Question Stats:
79% (01:36) correct
21%
(01:26)
wrong
based on 233
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Tough and Tricky questions: Ratios.
On a certain field trip, the ratio of teachers to students was 3 : 7. What was the number of parents on the field trip?
(1) On the field trip, the ratio of the number of students to parents was 5 : 1.
(2) The number of parents on the trip was less than 20.
Kudos for a correct solution.
14 Nov 2014, 11:32
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statement 1: not sufficient
We still need to know either the total # of people or a value for one of the groups.
statement 2: not sufficient
We don't know the relationship between #of parents and #of students/teachers
Down to answers C or E.
Combined, we can use statement 1 to find the ratio of all the groups. Both ratios we are given have students. One value for students is 5 and the other is 7 so we multiple together to get 35. For every 35 students, there will then be 15 teachers and 7 parents. Using statement 2, we know that the # of parents is less than 20. With the ratios we are given, the # of parents can be 7 or 14. So we still do not have enough information to know for sure.
Answer E!
We still need to know either the total # of people or a value for one of the groups.
statement 2: not sufficient
We don't know the relationship between #of parents and #of students/teachers
Down to answers C or E.
Combined, we can use statement 1 to find the ratio of all the groups. Both ratios we are given have students. One value for students is 5 and the other is 7 so we multiple together to get 35. For every 35 students, there will then be 15 teachers and 7 parents. Using statement 2, we know that the # of parents is less than 20. With the ratios we are given, the # of parents can be 7 or 14. So we still do not have enough information to know for sure.
Answer E!
15 Nov 2014, 02:20
Kudos
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Statement 1:
From question stem - The ratio of teachers(T) to students(S) was 3 : 7 => T/S = 3/7
From statement - The ratio of the number of students(S) to parents (P) was 5 : 1 => S/P = 5/1 => S = 5P
With the help of above two statements
T/5P = 3/7 => 7*T/15 =P ....... Not enough info
We don't know the number of teachers.
Insufficient. Hence option A & D are out.
Statement 2 :
The number of parents on the trip was less than 20 => P < 20
So,number of parents can be any number less than 20. 19,18,17 etc.
Insufficient. Hence option B is out.
By combining both the statements, we can't find number of parents.
Answer, E.
From question stem - The ratio of teachers(T) to students(S) was 3 : 7 => T/S = 3/7
From statement - The ratio of the number of students(S) to parents (P) was 5 : 1 => S/P = 5/1 => S = 5P
With the help of above two statements
T/5P = 3/7 => 7*T/15 =P ....... Not enough info
We don't know the number of teachers.
Insufficient. Hence option A & D are out.
Statement 2 :
The number of parents on the trip was less than 20 => P < 20
So,number of parents can be any number less than 20. 19,18,17 etc.
Insufficient. Hence option B is out.
By combining both the statements, we can't find number of parents.
Answer, E.
