1)In the xy plane,at what 2 points does the graph of y(x+a)(x+b) intersect the X axis?
A+B=-1
The graph intersects Y axis AT (0,-6)
2)What is the Avg of 11 conecutive integers
The avg of first nine integers is 7
The avg of last nine integers is 9
Guys i have no idea how to solve these problems.
DSQ
This topic has expert replies
- rijul007
- Legendary Member
- Posts: 588
- Joined: Sun Oct 16, 2011 9:42 am
- Location: New Delhi, India
- Thanked: 130 times
- Followed by:9 members
- GMAT Score:720
The avg of first nine integers is 7golu23 wrote: 2)What is the Avg of 11 conecutive integers
The avg of first nine integers is 7
The avg of last nine integers is 9
For 9 consecutive integers, 5th integer should be the integer
3,4,5,6,7,8,9,10,11
These are the first 9 integer, so the 11 consec int would be
3,4,5,6,7,8,9,10,11,12,13
Average = 8
The avg of last nine integers is 9
Similarly last 9 integers would be
5,6,7,8,9,10,11,12,13
The 11 integers would be
3,4,5,6,7,8,9,10,11,12,13
Average = 8
Option D
-
- Master | Next Rank: 500 Posts
- Posts: 265
- Joined: Mon Dec 28, 2009 9:45 pm
- Thanked: 26 times
- Followed by:2 members
- GMAT Score:760
Problem 1: can be rephrased asgolu23 wrote:1)In the xy plane,at what 2 points does the graph of y(x+a)(x+b) intersect the X axis?
A+B=-1
The graph intersects Y axis AT (0,-6)
2)What is the Avg of 11 conecutive integers
The avg of first nine integers is 7
The avg of last nine integers is 9
Guys i have no idea how to solve these problems.
y = (x+a)(x+b)
= x^2 +(a+b)x + ab
Stmt 1: a+b = -1. INSUFFICIENT as ab could be anything, thus changing the roots and hence the points where the graph meets the x axis.
Stmt 2: ab = -6, again a+b could be anything. Hence roots will change. Hence INSUFFICIENT.
Stmt 1 + Stmt 2: gives us a+b and ab thus now there will be unique roots for the equation. SUFFICIENT. Hence C
Problem 2:
Stmt 1: we know the sum of n numbers in an arithmetic progression is S = (n/2)(2a + (n-1)d), where n = number of terms, a = first term, d = difference between two consecutive terms.
From stmt 1, we know n = 9, S = 7*9, d = 1, hence a can be found hence Sum of 11 terms can be found. SUFFICIENT.
Stmt 2 - we see that again n, d and S are given hence Sum of 11 terms can be found. SUFFICIENT.
Hence D
Call me 1 - (412) 897 6727 (US) or leave a msg on BTG for GMAT advise / questions.
If you like the solution, check out my debrief at and leave a comment:
https://www.beatthegmat.com/760-done-dea ... 66740.html
If you like the solution, check out my debrief at and leave a comment:
https://www.beatthegmat.com/760-done-dea ... 66740.html
- golu23
- Senior | Next Rank: 100 Posts
- Posts: 54
- Joined: Sat Jul 09, 2011 5:34 pm
- Thanked: 1 times
- Followed by:1 members
1)A certain list consists of several integers. Is the product of integers in the list positive?
A)THE PRODUCT OF THE GREATEST AND THE SMALLEST IS POSITIVE
B)THERE IS AN EVEN NO OF INTEGERS IN THE LIST
2)Jane walked for 4 miles What was her avg speed for 2 miles?
a)HER AVG PEEED FOR 4 MILES WAS 3.2 KMPH
b)IT TOOK JANE 15 MINS LONGER TO WALK THE SECOND 2 MILES THAN FIRST 2 MILE
In problem 2 i know that first statement is not sufficient but i don't know how to use the second statement.
A)THE PRODUCT OF THE GREATEST AND THE SMALLEST IS POSITIVE
B)THERE IS AN EVEN NO OF INTEGERS IN THE LIST
2)Jane walked for 4 miles What was her avg speed for 2 miles?
a)HER AVG PEEED FOR 4 MILES WAS 3.2 KMPH
b)IT TOOK JANE 15 MINS LONGER TO WALK THE SECOND 2 MILES THAN FIRST 2 MILE
In problem 2 i know that first statement is not sufficient but i don't know how to use the second statement.