{"id":"cb_question_bank:527007bd-1add-4ad6-8945-cf22556c7289","source_id":"cb_question_bank","source_item_id":"527007bd-1add-4ad6-8945-cf22556c7289","external_id":null,"ibn":"029548-DC","question_id":"70feb725","program":"SAT","module":"math","domain_code":"H","domain":"Algebra","skill_code":"H.D.","skill":"Systems of two linear equations in two variables","difficulty":"H","score_band":6,"answer_type":"mcq","answer_source":"key","layout_warning":null,"form_id":null,"module_number":null,"position":null,"stem":"During a month, Morgan ran r miles at 5 miles per hour and biked b miles at 10 miles per hour. She ran and biked a total of 200 miles that month, and she biked for twice as many hours as she ran. What is the total number of miles that Morgan biked during the month?","stimulus":"","stimulus_html":null,"stem_html":"<p class=\"stem_paragraph \">During a month, Morgan ran <em class=\"inline_variable \">r</em>&nbsp;miles at 5&nbsp;miles per hour and biked <em class=\"inline_variable \">b</em>&nbsp;miles at 10&nbsp;miles per hour. She ran and biked a total of 200&nbsp;miles that month, and she biked for twice as many hours as she ran. What is the total number of miles that Morgan biked during the month?</p>\n","rationale_html":"<p>Choice D is correct. The number of hours Morgan spent running or biking can be calculated by dividing the distance she traveled during that activity by her speed, in miles per hour, for that activity. So the number of hours she ran can be represented by the expression <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/fc312d7234e86b7e1ad00490b8cb36e88f476323f7e9a3f2749426ce8e6e5694\" alt=\"the fraction r over 5\"></span>, and the number of hours she biked can be represented by the expression <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/a9cedf52b5d60e6a7bc1310e3ad5a900f555ac789de831bab94f7a9ff75083f4\" alt=\"the fraction b over 10\"></span>. It’s given that she biked for twice as many hours as she ran, so this can be represented by the equation <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/68be545e3b62d3e2ab549b4813491bc4975ead750e8d5e703a6d4a9c65dba6cd\" alt=\"the fraction b over 10, end fraction,  equals, 2 times the fraction r over 5\"></span>, which can be rewritten as <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/b491ff50a76f96ba68e15e640d5a812cfaabbcc2b7cb2219f7f360c546de43a8\" alt=\"b equals 4 r\"></span>. It’s also given that she ran <span class=\"italic\">r</span> miles and biked <span class=\"italic\">b</span> miles, and that she ran and biked a total of 200 miles. This can be represented by the equation <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/37f2a9d918ae044ecb8864cf2672ad0ab410ce772623b3120d45ae9b798209b9\" alt=\"r plus b, equals 200 \"></span>. Substituting <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/b41772589f7bcb4563455d0651a9892835d3e1f226abca5404a75c7bf96892c3\" alt=\"4 r\"></span> for <span class=\"italic\">b</span> in this equation yields <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/bcefefabe105e887aa1d5d547371e7716674214331ff563d48de23a74a1ba24a\" alt=\"r plus 4 r, equals 200 \"></span>, or <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/d63a9100ab3010ce2307c3ffe07f3c8c7e4b78f8264ccbee7997af1f095f4464\" alt=\"5 r equals 200\"></span>. Solving for <span class=\"italic\">r</span>&nbsp; yields <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/61467bdf507cd1263f2b4ab78b7961d73bc950241cc09c6acafac59d5e6379e4\" alt=\"r equals 40\"></span>. Determining the number of miles she biked, <span class=\"italic\">b</span>, can be found by substituting 40 for <span class=\"italic\">r</span> in <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/37f2a9d918ae044ecb8864cf2672ad0ab410ce772623b3120d45ae9b798209b9\" alt=\"r plus b, equals 200 \"></span>, which yields <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/49d81ab18e1749e74568e5588bac07867bd39b7c9e326e0b0e549e621ccc8deb\" alt=\"40 plus b, equals 200\"></span>. Solving for <span class=\"italic\">b</span> yields <span class=\"math-container\"><img align=\"middle\" role=\"math\" class=\"math-img\" src=\"/api/assets/1d5162740a58051b3e34ea6f8f38654a998382049ebf8788ee972c31f83d79aa\" alt=\"b equals 160\"></span>.</p><p>Choices A, B, and C are incorrect because they don’t satisfy that Morgan biked for twice as many hours as she ran. In choice A, if she biked 80 miles, then she ran 120 miles, which means she biked for 8 hours and ran for 24 hours. In choice B, if she biked 100 miles, then she ran 100 miles, which means she biked for 10 hours and ran for 20 hours. In choice C, if she biked 120 miles, then she ran for 80 miles, which means she biked for 12 hours and ran for 16 hours.</p><p>&nbsp;</p><p></p>\n","correct_answer":["D"],"has_media":true,"has_mathml":false,"has_table":false,"source_created_at":"2023-08-02T20:25:59.626000+00:00","source_updated_at":"2023-08-02T20:25:59.626000+00:00","options":[{"label":"A","content_html":"<p class=\"choice_paragraph \">80</p>\n","ord":0},{"label":"B","content_html":"<p class=\"choice_paragraph \">100</p>\n","ord":1},{"label":"C","content_html":"<p class=\"choice_paragraph \">120</p>\n","ord":2},{"label":"D","content_html":"<p class=\"choice_paragraph \">160</p>\n","ord":3}],"attribution":{"source_id":"cb_question_bank","source_name":"College Board digital SAT question bank (community dump)","rights_holder":"College Board","canonical_url":"https://satsuitequestionbank.collegeboard.org/","retrieved_from":"https://raw.githubusercontent.com/mdn522/sat-question-bank/main/data/cb-digital-questions.json","attribution":"SAT practice questions © College Board, from the official SAT Suite Question Bank. Retrieved via the community dump at github.com/mdn522/sat-question-bank.","disclaimer":"SAT® and PSAT/NMSQT® are trademarks registered by the College Board, which is not affiliated with, does not sponsor, and does not endorse this project.","license":"College Board copyright; source repository carries no licence. Local use only.","redistributable":false,"item_count":2017}}