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K and L are each four-digit positive integers with thousands [#permalink]
27 Jan 2012, 23:32

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Difficulty:

35% (medium)

Question Stats:

66% (02:49) correct
33% (02:47) wrong based on 158 sessions

K and L are each four-digit positive integers with thousands, hundreds, tens, and units digits defined as a, b, c, and d, respectively, for the number K, and p, q, r, and s, respectively, for the number L. For numbers K and L, the function W is defined as 5^a 2^b 7^c 3^d ÷ 5^p 2^q 7^r 3^s. The function Z is defined as (K – L) ÷ 10. If W = 16, what is the value of Z?

(A) 16 (B) 20 (C) 25 (D) 40 (E) It cannot be determined from the information given.

Re: K&L four digit positive integers [#permalink]
28 Jan 2012, 01:53

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Expert's post

enigma123 wrote:

K and L are each four-digit positive integers with thousands, hundreds, tens, and units digits defined as a, b, c, and d, respectively, for the number K, and p, q, r, and s, respectively, for the number L. For numbers K and L, the function W is defined as 5^a 2^b 7^c 3^d ÷ 5^p 2^q 7^r 3^s. The function Z is defined as (K – L) ÷ 10. If W = 16, what is the value of Z?

(A) 16 (B) 20 (C) 25 (D) 40 (E) It cannot be determined from the information given.

Given: w=\frac{5^a*2^b*7^c*3^d}{5^p*2^q*7^r*3^s}=16 --> w=5^{a-p}*2^{b-q}*7^{c-r}*3^{d-s}=2^4 --> the powers of 3, 5, and 7 must be zero and the power of 2 must be 4: a=p, b-q=4, c=r and d=s

Now, as thousands, tens, and units digits in K and L are equal and the difference between hundreds' digits is 4, then K-L=400 (for example K=1923 and L=1523 --> K-L=1923-1523=400).

K and L are each four-digit positive integers with thousands, hundreds, tens, and units digits defined as a, b, c, and d, respectively, for the number K, and p, q, r, and s, respectively, for the number L. For numbers K and L, the function W is defined as 5^a 2^b 7^c 3^d ÷ 5^p 2^q 7^r 3^s. The function Z is defined as (K – L) ÷ 10. If W = 16, what is the value of Z?

(A) 16 (B) 20 (C) 25 (D) 40 (E) It cannot be determined from the information given.

Given: w=\frac{5^a*2^b*7^c*3^d}{5^p*2^q*7^r*3^s}=16 --> w=5^{a-p}*2^{b-q}*7^{c-r}*3^{d-s}=2^4 --> the powers of 3, 5, and 7 must be zero and the power of 2 must be 4: a=p, b-q=4, c=r and d=s

Now, as thousands, tens, and units digits in K and L are equal and the difference between hundreds' digits is 4, then K-L=400 (for example K=1923 and L=1523 --> K-L=1923-1523=400).