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3

Apartado 3Bloque D

Responder a dos de los siguientes problemas (3.1, 3.2, 3.3):

Se ha realizado un estudio sobre los estudiantes de un Instituto de Educación Secundaria, recogiéndose distinta información, que se presenta a continuación.
3.1
De los 10001000 estudiantes matriculados en el instituto, 450450 son hombres, de los cuales un 12 %12\,\% son repetidores, mientras que, entre las mujeres, hay un 10 %10\,\% de repetidoras.
a
Escribir la información anterior en términos de sucesos y sus probabilidades asociadas. Hallar el porcentaje de estudiantes repetidores en el instituto.1 pt
b
Si se selecciona una persona repetidora, ¿cuál es la probabilidad de que sea hombre?1 pt
3.2
El equipo de profesores de Matemáticas Aplicadas a la Ciencias Sociales II ha calculado que el tiempo invertido por los estudiantes en hacer un examen sigue una distribución normal de media 100100 minutos y desviación típica igual a 1010 minutos.
a
¿Qué proporción de estudiantes realiza el examen en más de dos horas?1 pt
b
¿Cuánto tiempo tarda un estudiante en hacer el examen si el 88,1%88{,}1\% de sus compañeros tardan menos que él?1 pt
3.3
La dirección del instituto desea conocer cuál es el rendimiento medio de sus alumnos. Para ello, selecciona una muestra aleatoria de 100100 expedientes de estudiantes, obteniendo una calificación media muestral de 6,56{,}5 puntos. Asumiendo que la calificación sigue una distribución normal de media μ\mu y desviación igual a 11 punto, se pide:
a
¿Entre qué valores se encuentra la calificación media μ\mu de los estudiantes del instituto, con un nivel de confianza del 98%98\%?1 pt
b
Para un nivel de confianza del 99%99\%, ¿qué tamaño de muestra sería necesario para que el error cometido al estimar la media poblacional μ\mu no sea superior a los 0,50{,}5 puntos?1 pt

Formulario

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Distribución NormalF(x)=12π∫−∞xe−12t2 dtF(x)=\frac{1}{\sqrt{2\pi}}\int_{-\infty}^{x} e^{-\frac{1}{2}t^2}\,dt
Campana de la distribución normal rotulada F(x), con el área sombreada desde menos infinito hasta x, situado a la derecha de 0.
0,000,010,020,030,040,050,060,070,080,09
0,00,50000,50400,50800,51200,51600,51990,52390,52790,53190,5359
0,10,53980,54380,54780,55170,55570,55960,56360,56750,57140,5753
0,20,57930,58320,58710,59100,59480,59870,60260,60640,61030,6141
0,30,61790,62170,62550,62930,63310,63680,64060,64430,64800,6517
0,40,65540,65910,66280,66640,67000,67360,67720,68080,68440,6879
0,50,69150,69500,69850,70190,70540,70880,71230,71570,71900,7224
0,60,72570,72910,73240,73570,73890,74220,74540,74860,75170,7549
0,70,75800,76110,76420,76730,77040,77340,77640,77940,78230,7852
0,80,78810,79100,79390,79670,79950,80230,80510,80780,81060,8133
0,90,81590,81860,82120,82380,82640,82890,83150,83400,83650,8389
1,00,84130,84380,84610,84850,85080,85310,85540,85770,85990,8621
1,10,86430,86650,86860,87080,87290,87490,87700,87900,88100,8830
1,20,88490,88690,88880,89070,89250,89440,89620,89800,89970,9014
1,30,90320,90490,90660,90820,90990,91150,91310,91470,91620,9177
1,40,91920,92070,92220,92360,92510,92650,92790,92920,93060,9318
1,50,93320,93450,93570,93700,93820,93940,94060,94180,94290,9441
1,60,94520,94630,94740,94840,94950,95050,95150,95250,95350,9545
1,70,95540,95640,95730,95820,95910,95990,96080,96160,96250,9633
1,80,96410,96490,96560,96640,96710,96780,96860,96930,96990,9706
1,90,97130,97190,97260,97320,97380,97440,97500,97560,97610,9767
2,00,97720,97780,97830,97880,97930,97980,98030,98080,98120,9817
2,10,98210,98260,98300,98340,98380,98420,98460,98500,98540,9857
2,20,98610,98640,98680,98710,98750,98780,98810,98840,98870,9890
2,30,98930,98960,98980,99010,99040,99060,99090,99110,99130,9916
2,40,99180,99200,99220,99250,99270,99290,99310,99320,99340,9936
2,50,99380,99400,99410,99430,99450,99460,99480,99490,99510,9952
2,60,99530,99550,99560,99570,99590,99600,99610,99620,99630,9964
2,70,99650,99660,99670,99680,99690,99700,99710,99720,99730,9974
2,80,99740,99750,99760,99770,99770,99780,99790,99790,99800,9981
2,90,99810,99820,99820,99830,99840,99840,99850,99850,99860,9986
3,00,99870,99870,99870,99880,99880,99890,99890,99890,99900,9990
3,10,99900,99910,99910,99910,99920,99920,99920,99920,99930,9993
3,20,99930,99930,99940,99940,99940,99940,99940,99950,99950,9995
3,30,99950,99950,99950,99960,99960,99960,99960,99960,99960,9997
3,40,99970,99970,99970,99970,99970,99970,99970,99970,99970,9998
3,50,99970,99970,99980,99980,99980,99980,99980,99980,99980,9998
3,60,99980,99980,99990,99990,99990,99990,99990,99990,99990,9999
Distribución Binomialp(X=r)=(nr)pr(1−p)n−rp(X=r)=\binom{n}{r}p^r(1-p)^{n-r}
nnpp0,010,050,100,150,200,250,301/31/30,350,400,450,490,50
rr
200,98010,90250,81000,72250,64000,56250,49000,44440,42250,36000,30250,26010,2500
10,01980,09500,18000,25500,32000,37500,42000,44440,45500,48000,49500,49980,5000
20,00010,00250,01000,02250,04000,06250,09000,11110,12250,16000,20250,24010,2500
300,97030,85740,72900,61410,51200,42190,34300,29630,27460,21600,16640,13270,1250
10,02940,13540,24300,32510,38400,42190,44100,44440,44360,43200,40840,38230,3750
20,00030,00710,02700,05740,09600,14060,18900,22220,23890,28800,33410,36740,3750
30,00000,00010,00100,00340,00800,01560,02700,03700,04290,06400,09110,11760,1250
400,96060,81450,65610,52200,40960,31640,24010,19750,17850,12960,09150,06770,0625
10,03880,17150,29160,36850,40960,42190,41160,39510,38450,34560,29950,26000,2500
20,00060,01350,04860,09750,15360,21090,26460,29630,31050,34560,36750,37470,3750
30,00000,00050,00360,01150,02560,04690,07560,09880,11150,15360,20050,24000,2500
40,00000,00000,00010,00050,00160,00390,00810,01230,01500,02560,04100,05760,0625
500,95100,77380,59050,44370,32770,23730,16810,13170,11600,07780,05030,03450,0313
10,04800,20360,32810,39150,40960,39550,36020,32920,31240,25920,20590,16570,1563
20,00100,02140,07290,13820,20480,26370,30870,32920,33640,34560,33690,31850,3125
30,00000,00110,00810,02440,05120,08790,13230,16460,18110,23040,27570,30600,3125
40,00000,00000,00050,00220,00640,01460,02840,04120,04880,07680,11280,14700,1563
50,00000,00000,00000,00010,00030,00100,00240,00410,00530,01020,01850,02820,0313
600,94150,73510,53140,37710,26210,17800,11760,08780,07540,04670,02770,01760,0156
10,05710,23210,35430,39930,39320,35600,30250,26340,24370,18660,13590,10140,0938
20,00140,03050,09840,17620,24580,29660,32410,32920,32800,31100,27800,24360,2344
30,00000,00210,01460,04150,08190,13180,18520,21950,23550,27650,30320,31210,3125
40,00000,00010,00120,00550,01540,03300,05950,08230,09510,13820,18610,22490,2344
50,00000,00000,00010,00040,00150,00440,01020,01650,02050,03690,06090,08640,0938
60,00000,00000,00000,00000,00010,00020,00070,00140,00180,00410,00830,01380,0156
700,93210,69830,47830,32060,20970,13350,08240,05850,04900,02800,01520,00900,0078
10,06590,25730,37200,39600,36700,31150,24710,20480,18480,13060,08720,06040,0547
20,00200,04060,12400,20970,27530,31150,31770,30730,29850,26130,21400,17400,1641
30,00000,00360,02300,06170,11470,17300,22690,25610,26790,29030,29180,27860,2734
40,00000,00020,00260,01090,02870,05770,09720,12800,14420,19350,23880,26760,2734
50,00000,00000,00020,00120,00430,01150,02500,03840,04660,07740,11720,15430,1641
60,00000,00000,00000,00010,00040,00130,00360,00640,00840,01720,03200,04940,0547
70,00000,00000,00000,00000,00000,00010,00020,00050,00060,00160,00370,00680,0078
800,92270,66340,43050,27250,16780,10010,05760,03900,03190,01680,00840,00460,0039
10,07460,27930,38260,38470,33550,26700,19770,15610,13730,08960,05480,03520,0313
20,00260,05150,14880,23760,29360,31150,29650,27310,25870,20900,15690,11830,1094
30,00010,00540,03310,08390,14680,20760,25410,27310,27860,27870,25680,22730,2188
40,00000,00040,00460,01850,04590,08650,13610,17070,18750,23220,26270,27300,2734
50,00000,00000,00040,00260,00920,02310,04670,06830,08080,12390,17190,20980,2188
60,00000,00000,00000,00020,00110,00380,01000,01710,02170,04130,07030,10080,1094
70,00000,00000,00000,00000,00010,00040,00120,00240,00330,00790,01640,02770,0313
80,00000,00000,00000,00000,00000,00000,00010,00020,00020,00070,00170,00330,0039
900,91350,63020,38740,23160,13420,07510,04040,02600,02070,01010,00460,00230,0020
10,08300,29850,38740,36790,30200,22530,15560,11710,10040,06050,03390,02020,0176
20,00340,06290,17220,25970,30200,30030,26680,23410,21620,16120,11100,07760,0703
30,00010,00770,04460,10690,17620,23360,26680,27310,27160,25080,21190,17390,1641
40,00000,00060,00740,02830,06610,11680,17150,20480,21940,25080,26000,25060,2461
50,00000,00000,00080,00500,01650,03890,07350,10240,11810,16720,21280,24080,2461
60,00000,00000,00010,00060,00280,00870,02100,03410,04240,07430,11600,15420,1641
70,00000,00000,00000,00000,00030,00120,00390,00730,00980,02120,04070,06350,0703
80,00000,00000,00000,00000,00000,00010,00040,00090,00130,00350,00830,01530,0176
90,00000,00000,00000,00000,00000,00000,00000,00010,00010,00030,00080,00160,0020
1000,90440,59870,34870,19690,10740,05630,02820,01730,01350,00600,00250,00120,0010
10,09140,31510,38740,34740,26840,18770,12110,08670,07250,04030,02070,01140,0098
20,00420,07460,19370,27590,30200,28160,23350,19510,17570,12090,07630,04940,0439
30,00010,01050,05740,12980,20130,25030,26680,26010,25220,21500,16650,12670,1172
40,00000,00100,01120,04010,08810,14600,20010,22760,23770,25080,23840,21300,2051
50,00000,00010,00150,00850,02640,05840,10290,13660,15360,20070,23400,24560,2461
60,00000,00000,00010,00120,00550,01620,03680,05690,06890,11150,15960,19660,2051
70,00000,00000,00000,00010,00080,00310,00900,01630,02120,04250,07460,10800,1172
80,00000,00000,00000,00000,00010,00040,00140,00300,00430,01060,02290,03890,0439
90,00000,00000,00000,00000,00000,00000,00010,00030,00050,00160,00420,00830,0098
100,00000,00000,00000,00000,00000,00000,00000,00000,00000,00010,00030,00080,0010