← Back to Quizzes Hints: 2/2 Brain Teaser Set – 6 Hard Start Your name (optional): Share Certificate Browse Quizzes Play Again [{"type":"single","prompt":"Complete the sequence: 3, 7, 15, 31, 63, ?","options":["95","121","127","129"],"answer":[2],"explanation":"Pattern \u00d72 + 1 \u2192 next 63\u00d72+1 = 127.","hint":"Double then add one."},{"type":"single","prompt":"Which is different?","options":["Sine","Cosine","Tangent","Logarithm"],"answer":[3],"explanation":"First three are trigonometric ratios; Logarithm is not.","hint":"Topic grouping."},{"type":"single","prompt":"If \u00d7 means +, + means \u2212, and \u2212 means \u00d7, evaluate: 20 \u00d7 3 + 4 \u2212 5","options":["1","2","3","5"],"answer":[2],"explanation":"Replace \u2192 20+3 \u2212 4\u00d75 = 23 \u2212 20 = 3.","hint":"Substitute, then BODMAS."},{"type":"single","prompt":"Statements: Some A are B. No B are C. Some C are D.","options":["Only 1 follows","Only 2 follows","Both follow","Neither"],"answer":[0],"explanation":"The \u201csome A that are B\u201d cannot be C \u21d2 (1) true; (2) not necessary.","hint":"Use Venn restrictions."},{"type":"single","prompt":"Smallest number divisible by 12, 15, and 20?","options":["30","60","120","180"],"answer":[2],"explanation":"LCM(12,15,20) = 2\u00b2\u00d73\u00d75 = 60? Need \u00d72 for 20 \u2192 2\u00b3\u00d73\u00d75 = 120.","hint":"Prime factorization."},{"type":"single","prompt":"In how many distinct ways can the letters of \u201cLEVEL\u201d be arranged?","options":["20","24","30","60"],"answer":[2],"explanation":"5!\/(2!\u00d72!) = 120\/4 = 30.","hint":"Multiset permutations."},{"type":"single","prompt":"Solve: 2\/(x\u22121) + 3\/(x+1) = 5\/(x\u00b2\u22121)","options":["x = 1","x = \u22121","x = 6\/5","No solution"],"answer":[2],"explanation":"Combine over (x\u00b2\u22121): 2(x+1)+3(x\u22121)=5x\u22121 \u21d2 (5x\u22121)\/(x\u00b2\u22121)=5\/(x\u00b2\u22121) \u21d2 5x\u22121=5 \u21d2 x=6\/5.","hint":"Common denominator."},{"type":"single","prompt":"A price increases by 25% and then decreases by 20%. Net change?","options":["0%","+2%","+4%","\u22125%"],"answer":[0],"explanation":"1.25\u00d70.80 = 1.00 \u2192 no net change.","hint":"Multiply factors."},{"type":"single","prompt":"Two dice are thrown. Probability that the sum is 9?","options":["1\/12","1\/9","1\/8","5\/36"],"answer":[1],"explanation":"Favorable: (3,6),(4,5),(5,4),(6,3) \u2192 4\/36 = 1\/9.","hint":"Count ordered pairs."},{"type":"single","prompt":"A does a job in 12 days, B in 18 days. Together they take?","options":["6 days","7.2 days","8 days","9 days"],"answer":[1],"explanation":"1\/(1\/12 + 1\/18) = 1\/(5\/36) = 36\/5 = 7.2 days.","hint":"Add work rates."}]
