Last visit was: 18 Dec 2024, 04:06 It is currently 18 Dec 2024, 04:06
Decision Tracker
My Rewards
New comers' posts
New posts
Unanswered

Close

GRE Prep Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GRE score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Go to My Error Log Learn more
Close

Request Expert Reply

Confirm Cancel
PREVIOUS TOPIC
NEXT TOPIC

a, b, c, d, and e are five consecutive integers in increasin

Tags :
Find Similar Topics  About  Add a Tag

Show Tags
Hide Tags

User avatar
D
Carcass
Verbal Expert
Joined: 18 Apr 2015
Posts: 30353
Own Kudos [?]: 36747 [2]
Given Kudos: 26080
Send PM
a, b, c, d, and e are five consecutive integers in increasin [#permalink] New post   14 Apr 2018, 02:45
2
Expert Reply
00:00

Question Stats:

42% (01:33) correct 57% (01:27) wrong based on 54 sessions

Hide Show timer Statistics

a, b, c, d, and e are five consecutive integers in increasing order of size. Which one of the following expressions is not odd?

(A) a + b + c
(B) ab + c
(C) ab + d
(D) ac + d
(E) ac + e
ShowHide Answer
Official Answer
E
avatar
bellavarghese
Manager
Manager
Joined: 18 Jun 2019
Posts: 122
Own Kudos [?]: 42 [0]
Given Kudos: 0
Send PM
Re: a, b, c, d, and e are five consecutive integers in increasin [#permalink] New post   13 Sep 2019, 05:43
2
I don't think the answer is right.

If a,b,c,d,e, = 1,2,3,4,5
Then for A:
a+b+c=6 --> not odd.

Faulty question with not enough information?
avatar
orasheed01
Intern
Intern
Joined: 03 Dec 2019
Posts: 2
Own Kudos [?]: 0 [0]
Given Kudos: 0
Send PM
Re: a, b, c, d, and e are five consecutive integers in increasin [#permalink] New post   15 Dec 2019, 17:05
but if you start with an even integer such as 0 or 2 then A would not always be even. i.e. 0+1+2=3. I believe the OA is correct. If you think of it in terms of even and odds, E would always be an even integer.
avatar
S
pattypat
Manager
Manager
Joined: 23 Jul 2022
Posts: 66
Own Kudos [?]: 41 [0]
Given Kudos: 366
Re: a, b, c, d, and e are five consecutive integers in increasin [#permalink] New post   11 Aug 2022, 04:41
I am a bit confused about this question.
This is how I came up with the answer

First case: let a, b, c, d, e: odd (O), even (E), odd, even, odd (1,2,3,4,5)

(A) a + b + c = O + E + O = O
(B) ab + c = E + O = O
(C) ab + d = E + E = E for example, 1*2 + 4 = 6
(D) ac + d = O + E = O
(E) ac + e = O + O = E for example, 1*3 + 5 = 8

For the second case, I start with even, odd, even, odd, even for a, b, c, d, e. (2,3,4,5,6)

(A) a + b + c = E + O + E = O
(B) ab + c = O + E = O
(C) ab + d = E + O = O
(D) ac + d = E + O = O
(E) ac + e = E + E = E

So if we start with even, then the answer is E. But if I start with odd, I got both C and E...
I'm not sure with this question maybe my solution is wrong?
User avatar
D
Carcass
Verbal Expert
Joined: 18 Apr 2015
Posts: 30353
Own Kudos [?]: 36747 [1]
Given Kudos: 26080
Send PM
Re: a, b, c, d, and e are five consecutive integers in increasin [#permalink] New post   11 Aug 2022, 10:50
1
Expert Reply
OE


Quote:
Choice (A): a + b + c: Suppose a is an even number. Then b, the integer following a, must be odd, and c, the integer following b, must be even. Hence, a + b + c = sum of two even numbers (a and c) and an odd number (b). Since the sum of any number of even numbers with an odd number is odd (For example, if a = 4, then b = 5, c = 6, and a + b + c equals 4 + 5 + 6 = 15 (odd)), a + b + c is odd. Reject.

Choice (B): ab + c: At least one of every two consecutive positive integers a and b must be even. Hence, the product ab is an even number. Now, if c is odd (which happens when a is odd), ab + c must be odd. For example, if a = 3, b = 4, and c = 5, then ab + c must equal 12 + 5 = 17, an odd number. Reject.

Choice (C): ab + d: We know that ab being the product of two consecutive numbers must be even. Hence, if d happens to be an odd number (it happens when b is odd), then the sum ab + d is also odd. For example, if a = 4, then b = 5, c = 6, and d = 7, then ab + d = 3⋅ 5 + 7 = 15 + 7 = 23, an odd number. Reject.

Choice (D): ac + d: Suppose a is odd. Then c must also be odd, being a number 2 more than a. Hence, ac is the product of two odd numbers and must therefore be odd. Now, d is the integer following c and must be even. Hence, ac + d = odd + even = odd. For example, if a = 3, then b = 3 + 1 = 4, c = 4 + 1 = 5 (odd) and d = 5 + 1 = 6 (even) and ac + d = 3 ⋅ 5 + 6 = 21, an odd number. Reject.

Choice (E): ac + e: Suppose a is an odd number. Then both c and e must also be odd. Now, ac is product of two odd numbers and therefore must be odd. Summing this with another odd number e yields an even number. For example, if a = 1, then c must equal 3, and e must equal 5 and ac + e must equal 1 ⋅ 3 + 5 = 8, an even number. Now, suppose a is an even number. Then both c and e must also be even. Hence,

ac + e =

(product of two even numbers) + (an even number) =

(even number) + (even number) =

an even number
For example, if a = 2, then c must equal 4, and e must equal 6 and the expression ac + e equals 14, an even
number. Hence, in any case, ac + e is even. Correct.

The answer is (E).
avatar
S
pattypat
Manager
Manager
Joined: 23 Jul 2022
Posts: 66
Own Kudos [?]: 41 [1]
Given Kudos: 366
Re: a, b, c, d, and e are five consecutive integers in increasin [#permalink] New post   12 Aug 2022, 01:51
1
Carcass wrote:
OE


Quote:
Choice (A): a + b + c: Suppose a is an even number. Then b, the integer following a, must be odd, and c, the integer following b, must be even. Hence, a + b + c = sum of two even numbers (a and c) and an odd number (b). Since the sum of any number of even numbers with an odd number is odd (For example, if a = 4, then b = 5, c = 6, and a + b + c equals 4 + 5 + 6 = 15 (odd)), a + b + c is odd. Reject.

Choice (B): ab + c: At least one of every two consecutive positive integers a and b must be even. Hence, the product ab is an even number. Now, if c is odd (which happens when a is odd), ab + c must be odd. For example, if a = 3, b = 4, and c = 5, then ab + c must equal 12 + 5 = 17, an odd number. Reject.

Choice (C): ab + d: We know that ab being the product of two consecutive numbers must be even. Hence, if d happens to be an odd number (it happens when b is odd), then the sum ab + d is also odd. For example, if a = 4, then b = 5, c = 6, and d = 7, then ab + d = 3⋅ 5 + 7 = 15 + 7 = 23, an odd number. Reject.

Choice (D): ac + d: Suppose a is odd. Then c must also be odd, being a number 2 more than a. Hence, ac is the product of two odd numbers and must therefore be odd. Now, d is the integer following c and must be even. Hence, ac + d = odd + even = odd. For example, if a = 3, then b = 3 + 1 = 4, c = 4 + 1 = 5 (odd) and d = 5 + 1 = 6 (even) and ac + d = 3 ⋅ 5 + 6 = 21, an odd number. Reject.

Choice (E): ac + e: Suppose a is an odd number. Then both c and e must also be odd. Now, ac is product of two odd numbers and therefore must be odd. Summing this with another odd number e yields an even number. For example, if a = 1, then c must equal 3, and e must equal 5 and ac + e must equal 1 ⋅ 3 + 5 = 8, an even number. Now, suppose a is an even number. Then both c and e must also be even. Hence,

ac + e =

(product of two even numbers) + (an even number) =

(even number) + (even number) =

an even number
For example, if a = 2, then c must equal 4, and e must equal 6 and the expression ac + e equals 14, an even
number. Hence, in any case, ac + e is even. Correct.

The answer is (E).



Got it now. Thank you so much for the OE
Prep Club for GRE Bot
gmatclubot
Re: a, b, c, d, and e are five consecutive integers in increasin [#permalink]
12 Aug 2022, 01:51
Moderators:
adewale223
GRE Instructor
88 posts
bronaugust
GRE Forum Moderator
37 posts
BrushMyQuant
Moderator
1115 posts
VibhuAnurag
GRE Instructor
234 posts

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

Main navigation

Partners

GRE Resources

www.ets.org/gre | About | Terms and Conditions and Privacy Policy | Prep Club for GRE Rules | Contact