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100 points for $49 worth of Veritas practice GMATs FREE VERITAS PRACTICE GMAT EXAMS Earn 10 Points Per Post Earn 10 Points Per Thanks Earn 10 Points Per Upvote ## If 0.845 is an approximate solution for the equation 10^x = tagged by: fskilnik@GMATH ##### This topic has 1 expert reply and 0 member replies ### GMAT/MBA Expert ## If 0.845 is an approximate solution for the equation 10^x = ## Timer 00:00 ## Your Answer A B C D E ## Global Stats Difficult GMATH practice exercise (Quant Class 3) If 0.845 is an approximate solution for the equation 10^x = 7, which of the following fractions is closest to the solution of 7^(x+2) = 70? (A) 29/211 (B) 19/107 (C) 31/169 (D) 43/211 (E) 53/211 Answer: _____(C)__ _________________ Fabio Skilnik :: GMATH method creator ( Math for the GMAT) English-speakers :: https://www.gmath.net Portuguese-speakers :: https://www.gmath.com.br ### GMAT/MBA Expert GMAT Instructor Joined 09 Oct 2010 Posted: 1449 messages Followed by: 32 members Upvotes: 59 fskilnik@GMATH wrote: GMATH practice exercise (Quant Class 3) If 0.845 is an approximate solution for the equation 10^x = 7, which of the following fractions is closest to the solution of 7^(x+2) = 70? (A) 29/211 (B) 19/107 (C) 31/169 (D) 43/211 (E) 53/211 $${10^{0.845}} \cong 7$$ $${7^{x + 2}} = 70$$ $$?\,\, \cong x\,\,\,\,\,\,$$ $${7^{x + 2}} = 7 \cdot 10\,\,\,\,\, \Rightarrow \,\,\,\,\,{7^{x + 1}} = 10\,\,\,\,\, \Rightarrow \,\,\,\,\,{\left( {{7^{x + 1}}} \right)^{0.845}} = {10^{0.845}}\,\, \cong \,\,\,7$$ $${7^{0.845\left( {x + 1} \right)}} = {7^1}\,\,\,\, \Rightarrow \,\,\,\,\,x = {{1000} \over {845}} - 1 = {{155} \over {845}} = {{31} \over {169}}\,\,\,\, \Rightarrow \,\,\,\,\left( {\rm{C}} \right)$$ We follow the notations and rationale taught in the GMATH method. Regards, Fabio. _________________ Fabio Skilnik :: GMATH method creator ( Math for the GMAT) English-speakers :: https://www.gmath.net Portuguese-speakers :: https://www.gmath.com.br • Award-winning private GMAT tutoring Register now and save up to$200

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