BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Transaction for month of June

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Junior | Next Rank: 30 Posts
Posts: 15
Joined: Tue Oct 06, 2015 9:04 pm
Thanked: 1 times

Transaction for month of June

by moron » Thu Nov 19, 2015 8:23 pm
Date of Transaction Type of Transaction
June 11 Withdrawal of $350
June 16 Withdrawal of $500
June 21 Deposit $x

For certain savings account the table shows 3 transactions for month of June. The daily balance was recorded at the end of each of 30 days in
June. If daily balance was $1000 on June 1 and average (arithmetic means) for June was $1000. What was the amount of deposit on June 21?
Top
Source: — Problem Solving |
User avatar
Legendary Member
Posts: 2135
Joined: Mon Feb 03, 2014 9:26 am
Location: https://martymurraycoaching.com/
Thanked: 955 times
Followed by:140 members
GMAT Score:800

by MartyMurray » Thu Nov 19, 2015 8:46 pm
For a certain savings account, the table shows the three transactions for the month of June. The daily balance for the account was recorded at the end of each of the 30 days in June. If the daily balance was $1,000 on June 1 and if the average (arithmetic mean) of the daily balances for June was $1,000, what was the amount of the deposit on June 21?

A) $1,000
B) $1,150
C) $1,200
D) $1,450
E) $1,600

We need an average daily balance, which is the balance at the end of a day, of $1000 for the days in the month of June.

Average = Sum/Number

The Average we are seeking is 1000. The Number of days is 30. So the Sum of the daily balances has to be 30,000.

Simple enough.

June 1 - 10: $1000 in account at the end of each day -> 10 x 1000 = 10,000

June 11 - 15: $1000 - $350 = $650 in account at the end of each day -> 5 x 650 = 3250

June 16 - 20: $650 - $500 = $150 in account at the end of each day -> 5 x 150 = 750

Summing the daily balances for all of the days so far we get 10,000 + 3250 + 750 = 14,000.

To achieve a sum of 30,000 for the entire month we need 30,000 - 14,000 = 16,000 to be the sum of the remaining daily balances.

16,000/10 days = 1600. To get from a $150 daily balance to a $1600 daily balance, deposit $1450.

Choose D.
Last edited by MartyMurray on Fri Nov 20, 2015 3:51 am, edited 1 time in total.
Marty Murray
Perfect Scoring Tutor With Over a Decade of Experience
MartyMurrayCoaching.com
Contact me at [email protected] for a free consultation.
Top
Junior | Next Rank: 30 Posts
Posts: 15
Joined: Tue Oct 06, 2015 9:04 pm
Thanked: 1 times

by moron » Thu Nov 19, 2015 9:23 pm
Thanks.

What I fail to understand is
5 x 650 = 3250
and
5 x 150 = 750

Withdrawing $350 (June 11th) and $500(June 16th) seems like one time transaction . Where it is mentioned that it is a recurring transaction till the next transaction?
Top
User avatar
Legendary Member
Posts: 2135
Joined: Mon Feb 03, 2014 9:26 am
Location: https://martymurraycoaching.com/
Thanked: 955 times
Followed by:140 members
GMAT Score:800

by MartyMurray » Thu Nov 19, 2015 9:57 pm
It's not the transactions that are recurring. It's the daily balances, the amounts in the account, that recur.

If I put $1000 into an account, every day until money is added or removed there will be a balance of $1000.

So the average daily balance will be $1000.

If I withdraw $400, there will be $600 left. So every day until there is another transaction, there will be a balance of $600 and the average daily balance for the days after the withdrawal will be $600.

June 1 - Daily Balance: $1000

June 11 - Take $350 out. - Daily Balance For June 11 - $650

How much is in the account on June 12? Still $650.
Marty Murray
Perfect Scoring Tutor With Over a Decade of Experience
MartyMurrayCoaching.com
Contact me at [email protected] for a free consultation.
Top
User avatar
GMAT Instructor
Posts: 15539
Joined: Tue May 25, 2010 12:04 pm
Location: New York, NY
Thanked: 13060 times
Followed by:1906 members
GMAT Score:790

by GMATGuruNY » Fri Nov 20, 2015 1:48 am
Date of Transaction Type of Transaction
June 11 Withdrawal of $350
June 16 Withdrawal of $500
June 21 Deposit $x

For a certain savings account, the table shows the three transactions for the month of June. The daily balance for the account was recorded at the end of each of the 30 days in June. If the daily balance was $1,000 on June 1 and if the average (arithmetic mean) of the daily balances for June was $1,000, what was the amount of the deposit on June 21?

A. $1,000
B. $1,150
C. $1,200
D. $1,450
E. $1,600
The DAILY BALANCE is the amount in the account AT THE END OF THE DAY.
The AVERAGE DAILY BALANCE = (sum of the daily balances)/(number of days).
Thus:
SUM OF THE DAILY BALANCES = (number of days)(average daily balance).

Since the daily balance for the first 10 days ($1000) is the same as the average daily balance for the entire month ($1000), we can ignore the first 10 days.
We need to determine the amount that must be deposited on June 21 so that the average daily balance for the LAST twenty days is $1000.

Sum of the daily balances for June 11-30 = (number of days)(daily balance) = 20*1000 = 20,000.

When $350 is withdrawn on June 11, the daily balance decreases to $650.
Sum of the daily balances for June 11-15 = (number of days)(daily balance) = 5*650 = 3250.

When another $150 is withdrawn on June 16, the daily balance decreases to $500.
Sum of the daily balances for June 16-20 = (number of days)(daily balance) = 5*150 = 750.

Thus:
Sum of the daily balances for June 21-30 = (sum for June 11-30) - (sum for June 11-15) - (sum for 16-20) = 20,000 - 3250 - 750 = 16000.
Daily balance for June 21-30 = (sum of the daily balances)/(number of days) = 16,000/10 = 1600.

Since the daily balance on June 20 = 150, the amount deposited on June 21 = 1600-150 = 1450.

The correct answer is D.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
Top

GMAT/MBA Expert

User avatar
Elite Legendary Member
Posts: 10392
Joined: Sun Jun 23, 2013 6:38 pm
Location: Palo Alto, CA
Thanked: 2867 times
Followed by:511 members
GMAT Score:800

by [email protected] » Fri Nov 20, 2015 10:10 am
Hi All,

For this question, we have to deal with the average the daily balance at the END of each day for the entire 30 days.

For the first 10 days, the average is $1,000
For the next 5 days, the average is $650
For the next 5 days after, the average is $150
For the final 10 days, the average is $X

We're told that the average for the ENTIRE month is $1,000, so we need to use the Average Formula:

[10(1,000) + 5(650) + 5(150) + 10(X)]/30 = 1,000

This math can be done in a couple of different ways, but you'll eventually get to....

[14,000 + 10X]/30 = 1,000

14,000 + 10X = 30,000
10X = 16,000
X = 1600

Since X is the BALANCE for the last 10 days and there was already $150 in the account BEFORE the deposit was made, the deposit must be $1,450

Final Answer: D

GMAT assassins aren't born, they're made,
Rich
Contact Rich at [email protected]
Image
Top
Post new topic Post Reply
• Page 1 of 1