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# What is the value of 1/k + 1/r ? (1) k + r = 20 (2) kr = 64

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Math Expert
Joined: 02 Sep 2009
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What is the value of 1/k + 1/r ? (1) k + r = 20 (2) kr = 64  [#permalink]

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23 Sep 2018, 21:15
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Difficulty:

5% (low)

Question Stats:

89% (00:36) correct 11% (01:06) wrong based on 87 sessions

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What is the value of $$\frac{1}{k} + \frac{1}{r}$$ ?

(1) $$k + r = 20$$

(2) $$kr = 64$$

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Joined: 27 Aug 2018
Posts: 3
Re: What is the value of 1/k + 1/r ? (1) k + r = 20 (2) kr = 64  [#permalink]

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26 Sep 2018, 01:48
1/k + 1/r = (k +r)/kr
=> C. Both statements together are sufficient
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Joined: 31 Oct 2013
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Re: What is the value of 1/k + 1/r ? (1) k + r = 20 (2) kr = 64  [#permalink]

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26 Sep 2018, 04:17
Bunuel wrote:
What is the value of $$\frac{1}{k} + \frac{1}{r}$$ ?

(1) $$k + r = 20$$

(2) $$kr = 64$$

$$\frac{1}{k} + \frac{1}{r}$$

= $$\frac{k+r}{kr}$$

Statement 1 : k + r = 20. NOT sufficient . we don't know the value of kr.

Statement 2 : The same as 1. k + r is unknown.

(1+2) : Sufficient. we have the value of kr and k + r.

The best answer is C.
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Re: What is the value of 1/k + 1/r ? (1) k + r = 20 (2) kr = 64  [#permalink]

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16 Sep 2019, 03:21
1
Bunuel wrote:
What is the value of $$\frac{1}{k} + \frac{1}{r}$$ ?

(1) $$k + r = 20$$

(2) $$kr = 64$$

Asked: What is the value of $$\frac{1}{k} + \frac{1}{r}$$ ?
$$\frac{1}{k} + \frac{1}{r}$$
$$=\frac{k + r}{kr}$$

(1) $$k + r = 20$$
Since kr is unknown
NOT SUFFICIENT

(2) $$kr = 64$$
Since k + r is unknown
NOT SUFFICIENT

(1) + (2)
(1) $$k + r = 20$$
(2) $$kr = 64$$
$$\frac{1}{k} + \frac{1}{r}$$
$$=\frac{k + r}{kr}$$
$$=\frac{20}{64}$$
$$=\frac{5}{16}$$
SUFFICIENT

IMO C
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Re: What is the value of 1/k + 1/r ? (1) k + r = 20 (2) kr = 64  [#permalink]

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16 Sep 2019, 04:42
answer with zero calculations
the only thing we need is the following rule: if we have the same or more equations than variables, we can find the variable's value.

in order to answer the question, we need the value of both variables.
1) and 2) are each, on their own, an equation with two variables = infinite solutions, insufficient!
Together - 2 equations with 2 variables ==> definitely solvable! sufficient!
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Re: What is the value of 1/k + 1/r ? (1) k + r = 20 (2) kr = 64   [#permalink] 16 Sep 2019, 04:42
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# What is the value of 1/k + 1/r ? (1) k + r = 20 (2) kr = 64

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