GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 20 Aug 2018, 19:14

### 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

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

Track

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

Practice
Pays

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

# Mani saves money in a jar at home for six months. The first month he

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 48067
Mani saves money in a jar at home for six months. The first month he  [#permalink]

### Show Tags

25 Apr 2018, 21:51
00:00

Difficulty:

25% (medium)

Question Stats:

82% (02:12) correct 18% (02:51) wrong based on 34 sessions

### HideShow timer Statistics

Mani saves money in a jar at home for six months. The first month he saves S dollars. Each month thereafter, Mani saves 1/2 of what he has saved the previous month. If Mani’s total savings at the end of the six months is $393.75, how much money does he save the sixth month? (A)$6.25
(B) $7.50 (C)$12.50
(D) $18.75 (E)$25.00

_________________
Manager
Joined: 28 Nov 2017
Posts: 145
Location: Uzbekistan
Re: Mani saves money in a jar at home for six months. The first month he  [#permalink]

### Show Tags

25 Apr 2018, 22:34
Bunuel wrote:
Mani saves money in a jar at home for six months. The first month he saves S dollars. Each month thereafter, Mani saves 1/2 of what he has saved the previous month. If Mani’s total savings at the end of the six months is $393.75, how much money does he save the sixth month? (A)$6.25
(B) $7.50 (C)$12.50
(D) $18.75 (E)$25.00

$$S+\frac{1}{2}S+\frac{1}{4}S+\frac{1}{8}S+\frac{1}{16}S+\frac{1}{32}S=393\frac{3}{4}$$

$$\frac{63}{32}S=\frac{1575}{4}$$

Note that $$1575*4=6300$$.

So, $$S=200$$.

We are asked to find the amount of money he saved the sixth month. That is $$\frac{200}{32}=6.25$$

_________________

Kindest Regards!
Tulkin.

Manager
Joined: 24 Jun 2013
Posts: 98
Re: Mani saves money in a jar at home for six months. The first month he  [#permalink]

### Show Tags

25 Apr 2018, 22:42
Bunuel wrote:
Mani saves money in a jar at home for six months. The first month he saves S dollars. Each month thereafter, Mani saves 1/2 of what he has saved the previous month. If Mani’s total savings at the end of the six months is $393.75, how much money does he save the sixth month? (A)$6.25
(B) $7.50 (C)$12.50
(D) $18.75 (E)$25.00

he saves S in first month thereafter 1/2 of what he saved the previous month. so for six months

S+$$\frac{1}{2}$$S+$$\frac{1}{4}$$S+$$\frac{1}{8}$$S+$$\frac{1}{16}$$S+$$\frac{1}{32}$$S = 393.75

simplify we get , $$\frac{63}{32}$$S= 393.75

we are asked to find $$\frac{1}{32}$$S (Sixth month saving)

So $$\frac{S}{32}$$=$$\frac{393.75*32}{63*32}$$S= 6.25
_________________

If this post helped you learn something pls give kudos

Director
Joined: 02 Oct 2017
Posts: 616
Re: Mani saves money in a jar at home for six months. The first month he  [#permalink]

### Show Tags

13 May 2018, 10:14
Above question can be solved by two methods

I) S+ S/2 + S/4 +S/8+ S/16+ S/32= 393.75

Calculate S and then S/32 for last value

II) by calculating sum of gp with r=1/2

S((1/2)^6-1)/ (1/2-1)=393.75

63S/32=393.75

S=6.25*32

Last term =S*(1/2)^6=6.25

Give kudos if it helps to encourage me posting

Posted from my mobile device
BSchool Forum Moderator
Joined: 26 Feb 2016
Posts: 3054
Location: India
GPA: 3.12
Re: Mani saves money in a jar at home for six months. The first month he  [#permalink]

### Show Tags

13 May 2018, 12:44
Bunuel wrote:
Mani saves money in a jar at home for six months. The first month he saves S dollars. Each month thereafter, Mani saves 1/2 of what he has saved the previous month. If Mani’s total savings at the end of the six months is $393.75, how much money does he save the sixth month? (A)$6.25
(B) $7.50 (C)$12.50
(D) $18.75 (E)$25.00

Since Mani's total savings at the end of six months is $393.75 and he was able to save half of what he had saved the previous month, it is also safe to assume that the savings double each month(if we begin calculating from the last month) Let's consider Option A(6.25) as the amount he would have saved in the 6th month. So, the 5th month he would have saved xx.50 and every month after that he would have saved xx.00. The sum would be xxx.75 and could be our answer. Let's consider Option D(18.75). So in the 5th month, he would save xx.50 and there after every month he would save xx.00. The sum would be xxx.25. We can eliminate Option B,C, and E for similar reasons Therefore, Option A($6.25) is the amount Mani saves in the sixth month.
_________________

You've got what it takes, but it will take everything you've got

Target Test Prep Representative
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 2781
Re: Mani saves money in a jar at home for six months. The first month he  [#permalink]

### Show Tags

14 Jul 2018, 19:14
Bunuel wrote:
Mani saves money in a jar at home for six months. The first month he saves S dollars. Each month thereafter, Mani saves 1/2 of what he has saved the previous month. If Mani’s total savings at the end of the six months is $393.75, how much money does he save the sixth month? (A)$6.25
(B) $7.50 (C)$12.50
(D) $18.75 (E)$25.00

The first month Mani saves S dollars. The second month he saves 1/2 x S, or S/2 dollars. The third month he saves 1/2 x S/2, or S/4 dollars. In the fourth month he saves 1/2 x S/4, or S/8 dollars. Similarly, in the fifth and sixth months he saves S/16 and S/32 dollars, respectively.

With this information, we can create the equation:

S + S/2 + S/4 + S/8 + S/16 + S/32 = 393.75

Multiplying by 32, we have:

32S + 16S + 8S + 4S + 2S + S = 393.75 x 32

63S = 393.75 x 32

S = 200

So in the sixth month he saves 200 x 1/32 = \$6.25.

_________________

Jeffery Miller

GMAT Quant Self-Study Course
500+ lessons 3000+ practice problems 800+ HD solutions

Re: Mani saves money in a jar at home for six months. The first month he &nbs [#permalink] 14 Jul 2018, 19:14
Display posts from previous: Sort by

# Events & Promotions

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.