GMAT Questions Chat Group

PS Question 1 - July 5

How many integers less than 1000 have no factors (other than 1) in common with 1000 ?

A. 400
B. 401
C. 410
D. 420
E. 421

Source: GMAT Paper Tests | Difficulty: Hard

DS Question 1 - July 5

The base of the roof of a building has a pentagonal shape. The roof is constructed as a regular pyramid with a pentagon as its base. What is the total area of the lateral segments of the roof?

(1) The base of the pyramid has a perimeter of 30 meters.

(2) The faces of the pyramid are equal triangles.

Source: Manhattan GMAT | Difficulty: Hard

Answer is A, 400

Option E: Both statements are insufficient I guess

Both statements are insufficient

A 400

For data set 3,5,6,14 mean is 7 and std deviation is 4.18, if you add any value to dataset within range of 7+- 4.18 it will decrease std deviation. If you add a value outside this range std deviation will increase.

Note: above statement assumes values are added equidistant(so that meam remains same) from mean i.e.
7 in this case. Example 3 and 11 will decrease std deviation and 2 and 12 will increase std deviation .

A. 400

999 integers - 499 even (multiples of 2) - 100 (multiples of 5) = 400

Wouldn’t this mean that the question cannot uniquely be answered?/

Question can be answered uniquely if you have the values. If values are not available then it can be either case

Are not 100 ( Multiples of 10)?

No. The multiples of 10 which are even are removed in the first substraction. In 100, there are only 5s which come under odd category.

Since the question is clearly mentioning regular pyramid(meaning all edges are of equal length) and we can’t have regular pyramid with non-regular pentagon. Answer must be A and OA in the forum seems incorrect.

Focus on the formula of SD.
Firstly, Any new value is subtracted from the mean and squared. Thus, we are taking positive values.
Secondly, we divide by num of terms. Now use weighted mean logic. If the deviation of new value is more than the mean, SD will increase. If it’s less, then it will decrease.

Answer is A, basically all multiple of 2,5 are to be excluded as 1000 contains 2,5 in its prime factorization and we have to find all other numbers that don’t share any factors with 1000. So its

(All numbers 1 to 1000)-(Multiple of 5) - (Multiple of 2)

exclude multiple of 10 either from 2 or 5 to avoid double counting

In a college placement, 100 students attended an interview process and each of them got a job offer. 20 percent of the students who did not have a master’s degree got finance jobs. 25 percent of the students who got non-finance jobs have master’s degree. If 68 percent of the students got finance jobs, what percent of the students who attended the interview process have master’s degree

68-20 = 48 with jobs in finance + masters degree, 25 with non-finance jobs + masters degree, total = 48+25 = 73% students with masters degree

Total students who got a job offer = 100
“68 percent of the students got finance jobs “
Students in Finance = 68% of all students = 68% of 100 = 68
Students in Non-Finance = remaining students = 100-68 = 32
25 percent of the students who got non-finance jobs have master’s degree
25% of 32 = 8 students (in Non finance jobs) have a master’s degree.
Students in Non – Finance jobs without a master’s degree = 32-8 = 24.
20 percent of the students who did not have a master’s degree got finance jobs
Therefore 80% of students who did not have a master’s degree got Non finance jobs, which from the above statement is 24.
If 80% = 24, then 20% is 6.
Number of Finance students that have a master’s degree = 68-6 =62.

Total Number of students with a master’s degree = 62+8 =70.

It takes a minute with tables

Oh! I had missed that part " 25 percent of the students who got non-finance jobs have master’s degree". So, Students who got non-finance jobs with Master’s degree should be 32*25%= 8. So, the correct answer is 70% instead of 73%.

On monday , 150 customers visited a cafeteria. Each customer had a drink either hot or cold from the choice of either coffee pr tea or flavored milk.2/5 of the customers had cold beverages of which 20had coffee and 25 had tea. The ratio of the number of customers who had cold tea to the numbers of customers who had coffee is equal to the ratio of the numbers of customers who had tea to the number of customers who had coffee. If none of the customers had hot flavored milk, what percent of the customers who had hot drinks had coffee?

Can someone please show the steps to solving this? When I attempted it, I didn’t get whole numbers for the number of people who drink hot tea/coffee.

Also, I assumed it’s the number of people who had cold tea to COLD coffee. Is it supposed to be cold tea to the total number of people who had coffee (hot+cold)?