OG 12th Data Sufficiency 121-140

Question 121 – “In the xy-plane region R consists…”
OG Explanation is fine but you could graph it.
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Question 122 – “What is the volume of a certain…”
OG Explanation is fine.

Question 123 – “Joanna bought only $0.15 stamps and $0.29 stamps…”
OG Explanation is fine. This is harder problem than it looks.



Question 124 – “The table shows the results of a…”
OG Explanation is fine. Alternatively you could create a chart.

Question 125 – “If degree represents one of the operations…”
OG Explanation is fine.
Khan Academy (OG 11th) Question 89 – Begins at 5:00

Question 126 – “How many of the 60 cars sold last month…”
OG Explanation is fine.
Khan Academy (OG 11th) Question 90- Begins at 8:10

Question 127 – “In Jefferson School 300 students study French or Spanish…”
OG Explanation is fine.
Given: 100 students do not study French; this means 200 only study Spanish. In the first sentence, we are told all students study at least 1 language.

Statement 1: If 60 do not study Spanish, then 240 students do study Spanish. Since 200 students only study Spanish, this means that 40 students study both. SUFFICIENT.

Statement 2: This is essentially the same information. 240 Students study Spanish. Since 200 only study Spanish, this means 40 study both. SUFFICIENT.

The answer is D. Each statement ALONE is Sufficient.

Question 128 – “A school administrator will assign each student in a group of n students…”
OG Explanation is okay. We are told that m could be 4, 5, 6, 7, 8, 9, 10, 11, or 12. And that n > 14. “Is it possible to assign each of the n students to one of the m classrooms so that each classroom has the same number of students assigned to it” is the same as “is n divisible by m?” This is because there is no remainder (and hence divisibility) when the students are split up in equal numbers per group.

Statement 1: 3n is divisible by m. Consider if m=9, then n must only be divisible by 3. So we could n = 18 in which case we have 54 / 9 = 6 and 18 / 9 = 2. Or we could have n = 21 in which case we 63 / 9 = 7 but 21 / 9 is not an integer. INSUFFICIENT

Statement 2: 13 n is divisible by m. Because 13 is prime and 3 < m < 13, n must be divisible by m for the statement to hold. SUFFICIENT.

The answer is B.

Question 129 – “What is the median number of employees…”
OG Explanation is okay. We need to find the middle number.

Statement 1: 25% have 4 or more employees. Consider the following possibility: the other 75% could all have 1 employee per project (Median 1) or could all have 3 employees per project (Median 3). INSUFFICIENT.

Statement 2: 35% have 2 or fewer employees. Consider the following possibility: the other 65% projects could all have 3 employees (median 3) or could all have 4 employees (median 4). INSUFFICIENT.

Combining both statements: If 25% of projects have 4 or more employees and 35% have 2 or fewer employees, this means that the middle 40% have exactly 3 employees. (i.e. the first 35% have 2 or fewer employees, the next 40% have 3 employees, and the next 25% have 4 or more employees. The median (50%) mark occurs when there are exactly 3 employees per project). Both statements TOGETHER are sufficient. The answer ic C.



Question 130 – “If Juan had a doctor’s appointment on a certain day…”
OG Explanation is fine.
Khan Academy (OG 11th) Question 96 – Begins at 2:55

Question 131 – “When a player in a certain game tossed a coin….”
OG Explanation is fine.
Khan Academy (OG 11th) Question 100 – Begins at 2:00

Question 132 – “What is the value of x +y in the figure above …”
OG Explanation is okay.

Question 133 – “Are all the numbers in a certain list of 15 numbers…”
OG Explanation is okay. For statement 1, we could have 1+1+1+1+1+1+1+1+1+1+1+1
+1+1+46 = 60 or 4+4+4+4+4+4+4+4+4+4+4+4+4+4+4 = 60. INSUFFICIENT.
For statement2, if any 3 numbers in the list sum to 12. Then they must be equal if we have more than 3 numbers in our sequence. SUFFICIENT. I think intuition here is better than the laborious OG method.

Question 134 – “A scientist recorded the number of eggs in each…”
OG Explanation is fine.

Question 135 – “Quadrilateral RSTU shown above is a site plan…”
OG Explanation is fine.
Khan Academy (OG 11th) Question 102 – Begins at 6:55

Question 136 – “If the average (arithmetic mean) of six numbers…”
OG Explanation is fine.
Khan Academy (OG 11th) Question 104 – Begins at 2:00

Question 137 – “At a bakery, all donuts are priced equally…”
OG Explanation is fine.

Question 138 – “What was the total amount of revenue that…”
OG Explanation is fine.

Question 139 – “Any decimal that has only a finite number of nonzero…”
OG Explanation is fine.
Note: Terminating decimals can be expressed for x an integer as… x/10, x/100, x/1000, x/any power of ten. Therefore, a decimal is terminating if and only if the denominator can be expressed in the power of 2 and 5. Since 4 = (2^2)(5^0), statement 2 is sufficient.

Question 140 – “In the figure above, what is the value of…”
OG Explanation is fine.

Khan Academy (OG 11th) Question 108 – Begins at 4:10

One Response to OG 12th Data Sufficiency 121-140

  1. test says:

    Thanks to this I can see hacks, pentagrams, facebook cheats and keygens.

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