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

 It is currently 17 Oct 2018, 13:49

### 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

# If x ≥ 0.9, which of the following could be the value of 1/(x^(1/2))

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 49968
If x ≥ 0.9, which of the following could be the value of 1/(x^(1/2))  [#permalink]

### Show Tags

20 Sep 2018, 00:57
00:00

Difficulty:

55% (hard)

Question Stats:

58% (01:35) correct 42% (01:49) wrong based on 53 sessions

### HideShow timer Statistics

If x ≥ 0.9, which of the following could be the value of $$\frac{1}{\sqrt{x}}$$?

(A) 1.02
(B) 1.12
(C) 1.23
(D) 1.45
(E) 2.1

_________________
Math Expert
Joined: 02 Aug 2009
Posts: 6956
If x ≥ 0.9, which of the following could be the value of 1/(x^(1/2))  [#permalink]

### Show Tags

20 Sep 2018, 03:05
Bunuel wrote:
If x ≥ 0.9, which of the following could be the value of $$\frac{1}{\sqrt{x}}$$?

(A) 1.02
(B) 1.12
(C) 1.23
(D) 1.45
(E) 2.1

Do we require to solve it.....NO

The question can have only two extremes as the answer, so it will be A or E. If the question finally means MAX possible, it will be the lowest so A AND if it means minimum possible, ans is E
So what can be the best way without any calculations..
x is increasing, so √x will also increase as we are generally looking at the value of X above 1..
If √x is increasing, $$\frac{1}{√x}$$ will decrease. So we are looking for the MAX possible
So if there is ONLY one choice that fits in, it will be the smallest, so A.
Say if B was possible, then A being smaller would surely be possible too.

A
_________________

1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html

GMAT online Tutor

Director
Joined: 14 Dec 2017
Posts: 500
GMAT 1: 640 Q49 V28
Re: If x ≥ 0.9, which of the following could be the value of 1/(x^(1/2))  [#permalink]

### Show Tags

20 Sep 2018, 06:36
Bunuel wrote:
If x ≥ 0.9, which of the following could be the value of $$\frac{1}{\sqrt{x}}$$?

(A) 1.02
(B) 1.12
(C) 1.23
(D) 1.45
(E) 2.1

In general, it is handy to know that

for $$0 < x < 1$$, $$x < \sqrt{x} < 1$$

for $$x > 1$$, $$1 < \sqrt{x} < x$$

Using these properties,

For $$x = 0.9$$ , we know $$\sqrt{x} < 1$$, hence $$\frac{1}{\sqrt{x}} > 1$$

$$\frac{1}{\sqrt{x}}$$ = $$\sqrt{{\frac{10}{9}}}$$ = $$\sqrt{1.11}$$

For $$x = 1$$, we get, $$\frac{1}{\sqrt{x}} = 1$$

For any $$x > 1$$, we get, $$\frac{1}{\sqrt{x}} < 1$$

Hence out of the answer choices, the only value less than 1.11 is 1.02

Thanks,
GyM
_________________
CEO
Joined: 08 Jul 2010
Posts: 2537
Location: India
GMAT: INSIGHT
WE: Education (Education)
If x ≥ 0.9, which of the following could be the value of 1/(x^(1/2))  [#permalink]

### Show Tags

20 Sep 2018, 21:34
1
Bunuel wrote:
If x ≥ 0.9, which of the following could be the value of $$\frac{1}{\sqrt{x}}$$?

(A) 1.02
(B) 1.12
(C) 1.23
(D) 1.45
(E) 2.1

$$x ≥ 0.9$$
i.e. $$1/x ≤ 1/0.9$$
i.e. $$1/x ≤ 1.11$$
taking square root both sides
i.e. $$√(1/x) ≤ √1.11$$
i.e. $$√(1/x) ≤ 1.11$$

CONCEPT: For any value of x such that 0 < x < 1, The square root of the value will be bigger than value i.e. $$√x > x$$ and square will be smaller than value i.e. $$x^2 < x$$
_________________

Prosper!!!
GMATinsight
Bhoopendra Singh and Dr.Sushma Jha
e-mail: info@GMATinsight.com I Call us : +91-9999687183 / 9891333772
Online One-on-One Skype based classes and Classroom Coaching in South and West Delhi
http://www.GMATinsight.com/testimonials.html

ACCESS FREE GMAT TESTS HERE:22 ONLINE FREE (FULL LENGTH) GMAT CAT (PRACTICE TESTS) LINK COLLECTION

If x ≥ 0.9, which of the following could be the value of 1/(x^(1/2)) &nbs [#permalink] 20 Sep 2018, 21:34
Display posts from previous: Sort by