Forum Home > GMAT > Quantitative > Problem Solving (PS)
Events & Promotions
|
|
GMAT 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
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Dec 1310:00 AM EST
-12:00 PM EST
Have you ever wondered how to score a PERFECT 805 on the GMAT? Meet Julia, a banking professional who used the Target Test Prep course to achieve this incredible feat. Julia's story is nothing short of an inspiration.
Dec 1410:00 AM EST
-12:00 PM EST
Think a 100% GMAT Verbal score is out of your reach? Target Test Prep will make you think again! Our course uses techniques such as topical study and spaced repetition to maximize knowledge retention and make studying simple and fun.
Dec 1411:00 AM IST
-01:00 PM IST
Attend this session to learn how to Deconstruct arguments, Pre-Think Author’s Assumptions, and apply Negation Test.- Dec 15
11:00 AM IST
-01:00 PM IST
Attend this free GMAT Algebra Webinar and learn how to master the most challenging Inequalities and Absolute Value problems with ease. 
Dec 1608:00 AM PST
-11:59 PM PST
GMAT Club 12 Days of Christmas is a 4th Annual GMAT Club Winter Competition based on solving questions. This is the Winter GMAT competition on GMAT Club with an amazing opportunity to win over $40,000 worth of prizes!
11 Feb 2021, 08:45
Kudos
Bookmarks
C
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
55%
(hard)
Question Stats:
64% (02:49) correct
36%
(02:46)
wrong
based on 73
sessions
History
Date
Time
Result
Not Attempted Yet
What is the number of seven digit integers, with sum of the digits equal to 10 and formed by using the digits 1, 2 and 3 only?
(A) 55
(B) 66
(C) 77
(D) 88
(E) 99
Are You Up For the Challenge: 700 Level Questions: 700 Level Questions
(A) 55
(B) 66
(C) 77
(D) 88
(E) 99
Are You Up For the Challenge: 700 Level Questions: 700 Level Questions
Foreheadson
Joined: 22 Jun 2020
Last visit: 24 Sep 2022
Posts: 154
Own Kudos:
Given Kudos: 120
Location: Georgia
Concentration: Finance, General Management
Schools: Booth '25 (WL) Darden '25
GMAT 1: 720 Q51 V38
GPA: 3.71
11 Feb 2021, 09:17
Kudos
Bookmarks
the number can include only one 3, otherwise 3+3=6, even if all other 5 digits equal 1, sum is 11.
So if the number includes 3, it must also include exactly one 2 and all other digits should be 1.
number of ways to write the number using this numbers is 7P2=42
the number may also invlude three 2s and four 1s. because 2s are the same we need 3C7=35
42+35=77, which is C.
Posted from my mobile device
So if the number includes 3, it must also include exactly one 2 and all other digits should be 1.
number of ways to write the number using this numbers is 7P2=42
the number may also invlude three 2s and four 1s. because 2s are the same we need 3C7=35
42+35=77, which is C.
Posted from my mobile device
wishmasterdj
Joined: 04 May 2016
Last visit: 25 Oct 2021
Posts: 95
Own Kudos:
Given Kudos: 10
Location: India
Schools: ISB '18 (A)
GMAT 1: 700 Q48 V37
GPA: 3.2
11 Feb 2021, 18:58
Kudos
Bookmarks
2 cases are possible:
1. 1111123 - 7!/5! = 42
2. 1111222 - 7!/4!*3! = 35
Hence 77 (C)
Alternatively, think in terms of Permutations - In such questions, since the sum constraint is provided, you ALREADY know WHICH digits to pick since the number of cases is delineated so, all you have to do is pick arrangements.
Hence 7P2 + 7P3 should cover both cases.
Think about it
1. 1111123 - 7!/5! = 42
2. 1111222 - 7!/4!*3! = 35
Hence 77 (C)
Alternatively, think in terms of Permutations - In such questions, since the sum constraint is provided, you ALREADY know WHICH digits to pick since the number of cases is delineated so, all you have to do is pick arrangements.
Hence 7P2 + 7P3 should cover both cases.
Think about it
