{ "query": { "display": "C(145, 9)", "symbolab_question": "#C(145,9)" }, "solution": { "level": "PERFORMED", "subject": "Statistics", "topic": "nCr", "subTopic": "Other", "default": "\\frac{2.19946E19}{362880}" }, "steps": { "type": "interim", "title": "$$145\\:nCr\\:9:{\\quad}\\frac{2.19946E19}{362880}$$", "steps": [ { "type": "definition", "title": "n choose r", "text": "Gives the number of subsets of r elements, out of n elements<br/>$$nCr=\\frac{n!}{r!\\left(n-r\\right)!}$$" }, { "type": "step", "result": "=\\frac{n!}{r!\\left(n-r\\right)!}" }, { "type": "step", "primary": "Plug in $$n=145,\\:r=9$$", "result": "=\\frac{145!}{9!\\left(145-9\\right)!}" }, { "type": "interim", "title": "$$\\frac{145!}{9!\\left(145-9\\right)!}=\\frac{2.19946E19}{362880}$$", "input": "\\frac{145!}{9!\\left(145-9\\right)!}", "result": "=\\frac{2.19946E19}{362880}", "steps": [ { "type": "step", "primary": "Subtract the numbers: $$145-9=136$$", "result": "=\\frac{145!}{9!\\cdot\\:136!}" }, { "type": "step", "primary": "Cancel the factorials: $$\\frac{n!}{\\left(n-m\\right)!}=n\\cdot\\left(n-1\\right)\\cdots\\left(n-m+1\\right),\\:n>m$$", "secondary": [ "$$\\frac{145!}{136!}=145\\cdot\\:144\\cdot\\:143\\cdot\\:142\\cdot\\:141\\cdot\\:140\\cdot\\:139\\cdot\\:138\\cdot\\:137$$" ], "result": "=\\frac{145\\cdot\\:144\\cdot\\:143\\cdot\\:142\\cdot\\:141\\cdot\\:140\\cdot\\:139\\cdot\\:138\\cdot\\:137}{9!}" }, { "type": "step", "primary": "Refine", "result": "=\\frac{2.19946E19}{9!}" }, { "type": "interim", "title": "$$9!=362880$$", "input": "9!", "steps": [ { "type": "step", "primary": "Apply factorial rule: $$n!=1\\cdot2\\cdot3\\cdot\\ldots\\cdot\\:n$$", "secondary": [ "$$9!=1\\cdot\\:2\\cdot\\:3\\cdot\\:4\\cdot\\:5\\cdot\\:6\\cdot\\:7\\cdot\\:8\\cdot\\:9$$" ], "result": "=1\\cdot\\:2\\cdot\\:3\\cdot\\:4\\cdot\\:5\\cdot\\:6\\cdot\\:7\\cdot\\:8\\cdot\\:9" }, { "type": "step", "primary": "Multiply the numbers: $$1\\cdot\\:2\\cdot\\:3\\cdot\\:4\\cdot\\:5\\cdot\\:6\\cdot\\:7\\cdot\\:8\\cdot\\:9=362880$$", "result": "=362880" } ], "meta": { "solvingClass": "Solver" } }, { "type": "step", "result": "=\\frac{2.19946E19}{362880}" } ], "meta": { "solvingClass": "Solver" } } ] } }