Answer Happy

An electrical firm manufactures light bulbs that have a length of life that is approximately normally distributed with a standard deviation of 25 hours. If a sample of 35 bulbs has an average life of 770 hours, find a 96% confidence interval for the population mean of all bulbs produced by this firm. Click here to view page 1 of the standard normal distribution table Click here to view page 2 of the standard normal distribution table. Click here to view page 1 of the table of critical values of the t-distribution. Click here to view page 2 of the table of critical values of the t-distribution. The confidence interval is<μ<. (Round to the nearest integer as needed.) ()
Standard Normal Distribution Table (Page 1) Arga Areas under the Normal Curve .01 .02 .03 .04 .05 .06 .07 .08 0.0038 0.0037 0.0036 -2.6 0.0051 0.0049 0.0048 -2.5 0.0068 0.0066 .00 -3.4 0.0003 0.0003 0.0003 0.0003 0.0003 0.0003 0.0003 0.0003 0.0003 -3.3 0.0005 0.0005 0.0005 0.0004 0.0004 0.0004 0.0004 0.0004 0.0004 -3.2 0.0007 0.0007 0.0006 0.0006 0.0006 0.0006 0.0006 0.0005 0.0005 -3.1 0.0010 0.0009 0.0009 0.0009 0.0008 0.0008 0.0008 0.0008 0.0007 -3.0 0.0013 0.0013 0.0013 0.0012 0.0012 0.0011 0.0011 0.0011 0.0010 -2.9 0.0019 0.0018 0.0018 0.0017 0.0016 0.0016 0.0015 0.0015 0.0014 0.0014 -2.9 -2.8 0.0026 0.0025 0.0024 0.0023 0.0023 0.0022 0.0021 0.0021 0.0020 0.0019 -2.8 -2.7 0.0035 0.0034 0.0033 0.0032 0.0031 0.0030 0.0029 0.0028 0.0027 0.0026 -2.7 -2.6 0.0047 0.0045 0.0044 0.0043 0.0041 0.0040 0.0039 -2.5 0.0062 0.0060 0.0059 0.0057 0.0055 0.0054 0.0052 -2.4 0.0082 0.0080 0.0078 0.0075 0.0073 0.0071 0.0069 0.0064 -2.4 -2.3 0.0107 0.0104 0.0102 0.0099 0.0096 0.0094 0.0091 0.0089 0.0087 0.0084 -2.3 -2.2 0.0139 0.0136 0.0132 0.0129 0.0125 0.0122 0.0119 0.0116 0.0113 0.0110 -2.2 -2.1 0.0179 0.0174 0.0170 0.0166 0.0162 0.0158 0.0154 0.0150 0.0146 0.0143 -2.1 -2.0 0.0228 0.0222 0.0217 0.0212 0.0207 0.0202 0.0197 0.0192 0.0188 0.0183 -2.0 -1.9 0.0287 0.0281 0.0274 0.0268 0.0262 0.0256 0.0250 0.0244 0.0239 0.0233 -1.9 -1.8 0.0359 0.0351 0.0344 0.0336 0.0329 0.0322 0.0314 0.0307 0.0301 0.0294 -1.8 -1.7 0.0446 0.0436 0.0427 0.0418 0.0409 0.0401 0.0392 0.0384 0.0375 0.0367 -1.7 -1.6 0.0548 0.0537 0.0526 0.0516 0.0505 0.0495 0.0485 0.0475 0.0465 0.0455 -1.6 -1.5 0.0668 0.0655 0.0643 0.0630 0.0618 0.0606 0.0594 0.0582 0.0571 0.0559 -1.5 -1.4 0.0808 0.0793 0.0778 0.0764 0.0749 0.0735 0.0721 0.0708 0.0694 0.0681 -1.4 -1.3 0.0968 0.0951 0.0934 0.0918 0.0901 0.0885 0.0869 0.0853 0.0838 0.0823 -1.3 -1.2 0.1151 0.1131 0.1112 0.1093 0.1075 0.1056 0.1038 0.1020 0.1003 0.0985 -1.2 -1.1 0.1357 0.1335 0.1314 0.1292 0.1271 0.1251 0.1230 0.1210 0.1190 0.1170 -1.1 -1.0 0.1587 0.1562 0.1539 0.1515 0.1492 0.1469 0.1446 0.1423 0.1401 0.1379 -1.0 -0.9 0.1841 0.1814 0.1788 0.1762 0.1736 0.1711 0.1685 0.1660 0.1635 -0.8 0.2119 0.2090 0.2061 0.2033 0.2005 0.1977 0.1949 0.1922 0.1894 0.1867 -0.8 -0.7 0.2420 0.2389 0.2358 0.2327 0.2296 0.2266 0.2236 0.2206 0.2177 0.2148 -0.7 -0.6 0.2743 0.2709 0.2676 0.2643 0.2611 0.2578 0.2546 0.2514 0.2483 0.2451 -0.6 -0.5 0.3085 0.3050 0.3015 0.2981 0.2946 0.2912 0.2877 0.2843 0.2810 0.2776 -0.5 -0.4 0.3446 0.3409 0.3372 0.3336 0.3300 0.3264 0.3228 0.3192 0.3156 0.3121 -0.4 -0.3 0.3821 0.3783 0.3745 0.3707 0.3669 0.3632 0.3594 0.3557 0.3520 0.3483 -0.3 -0.2 0.4207 0.4168 0.4129 0.4090 0.4052 0.4013 0.3974 0.3936 0.3897 0.3859 -0.2 -0.1 0.4602 0.4562 0.4522 0.4483 0.4443 -0.0 0.5000 0.4960 0.4920 0.4880 0.4840 .02 0.1611 -0.9 0.4404 0.4364 0.4325 0.4286 0.4247 -0.1 0.4641 -0.0 0.4801 0.4761 0.4721 0.4681 .00 .01 .03 .04 .05 .06 .07 .08 .09 z .09 0.0002 -3.4 0.0003 -3.3 0.0005 -3.2 0.0007 -3.1 0.0010 -3.0 I
Standard Normal Distribution Table (Page 2) Areas under the Normal Curve .00 .01 .02 .03 .04 .05 .06 .07 .08 .09 0.5557 0.5596 0.5 0.6 0.0 0.5000 0.5040 0.5080 0.5120 0.5160 0.5199 0.5239 0.5279 0.5319 0.5359 0.0 0.1 0.5398 0.5438 0.5478 0.5517 0.5636 0.5675 0.5714 0.5753 0.1 0.2 0.5793 0.5832 0.5871 0.5910 0.5948 0.5987 0.6026 0.6064 0.6103 0.6141 0.2 0.3 0.6179 0.6217 0.6255 0.6293 0.6331 0.6368 0.6406 0.6443 0.6480 0.6517 0.3 0.4 0.6554 0.6591 0.6628 0.6664 0.6700 0.6736 0.6772 0.6808 0.6844 0.6879 0.4 0.5 0.6915 0.6950 0.6985 0.7019 0.7054 0.7088 0.7123 0.7157 0.7190 0.7224 0.6 0.7257 0.7291 0.7324 0.7357 0.7389 0.7422 0.7454 0.7486 0.7517 0.7549 0.7 0.7580 0.7611 0.7642 0.7673 0.7704 0.7734 0.7764 0.7794 0.7823 0.7852 0.7 0.8 0.7881 0.7910 0.7939 0.7967 0.7995 0.8023 0.8051 0.8078 0.8106 0.8133 0.8 0.9 0.8159 0.8186 0.8212 0.8238 0.8264 0.8289 0.8315 0.8340 0.8365 0.8389 0.9 1.0 0.8413 0.8438 0.8461 0.8485 0.8508 0.8531 0.8554 0.8577 0.8599 0.8621 1.0 1.1 0.8643 0.8665 0.8686 0.8708 0.8729 0.8749 0.8770 0.8790 0.8810 0.8830 1.1 1.2 0.8849 0.8869 0.8888 0.8907 0.8925 0.8944 0.8962 0.8980 0.8997 0.9015 1.2 0.9115 0.9131 0.9147 0.9162 0.9177 1.3 0.9265 0.9279 0.9292 0.9306 0.9319 1.4 0.9394 0.9406 0.9418 0.9429 0.9441 1.5 0.9505 0.9515 0.9525 0.9535 0.9545 1.6 0.9616 0.9625 0.9633 1.7 1.3 0.9032 0.9049 0.9066 0.9082 0.9099 1.4 0.9192 0.9207 0.9222 0.9236 0.9251 0.9370 0.9382 0.9484 0.9599 0.9608 0.9934 0.9936 2.4 1.5 0.9332 0.9345 0.9357 1.6 0.9452 0.9463 0.9474 0.9495 1.7 0.9554 0.9564 0.9573 0.9582 0.9591 1.8 0.9641 0.9649 0.9656 0.9664 0.9671 0.9678 0.9686 0.9693 0.9699 0.9706 1.8 1.9 0.9713 0.9719 0.9726 0.9732 0.9738 0.9744 0.9750 0.9756 0.9761 0.9767 1.9 2.0 0.9772 0.9778 0.9783 0.9788 0.9793 0.9798 0.9803 0.9808 0,9812 0,9817 2.0 2.1 0.9821 0.9826 0.9830 0.9834 0.9838 0.9842 0.9846 0.9850 0.9854 0.9857 2.1 2.2 0.9861 0.9864 0.9868 0.9871 0.9875 0.9878 0.9881 0.9884 0.9887 0.9890 2.2 2.3 0.9893 0.9896 0.9898 0.9901 0.9904 0.9906 0.9909 0.9911 0.9913 0.9916 2.3 2.4 0.9918 0.9920 0.9922 0.9925 0.9927 0.9929 0.9931 0.9932 2.5 0.9938 0.9940 0.9941 0.9943 0.9945 0.9946 0.9948 0.9949 0.9951 0.9952 2.5 2.6 0.9953 0.9955 0.9956 0.9957 0.9959 0.9960 0.9961 0.9962 0.9963 0.9964 2.6 2.7 0.9965 0.9966 0.9967 0.9968 0.9969 0.9970 0.9971 0.9972 0.9973 0.9974 2.7 2.8 0.9974 0.9975 0.9976 0.9977 0.9977 0.9978 0.9979 0.9979 0.9980 0.9981 2.8 2.9 0.9981 0.9982 0.9982 0.9983 0.9984 0.9984 0.9985 0.9985 0.9986 0.9986 2.9 3.0 0.9987 0.9987 0.9987 0.9988 0.9988 0.9989 0.9989 3.1 0.9990 0.9991 0.9991 0.9991 0.9992 0.9992 0.9992 3.2 0.9993 0.9993 0.9994 0.9994 0.9994 0.9994 0.9994 0.9995 3.3 0.9995 0.9995 0.9995 0.9996 0.9996 0.9996 0.9996 0.9996 3.4 0.9997 0.9997 0.9997 0.9997 0.9997 0.9997 .00 .01 .02 0.9989 0.9990 0.9990 3.0 0.9992 0.9993 0.9993 3.1 0.9995 0.9995 3.2 0.9996 0.9997 3.3 0.9997 0.9997 0.9997 0.9998 3.4 .03 .04 .05 .06 .07 .08 .09 I
Critical Values of the t-Distribution (Page 1) 0 Critical Values of the t-Distribution t 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 40 60 120 0.40 0.325 0.289 0.277 0.271 0.267 0.265 0.263 0.262 0.261 0.260 0.260 0.259 0.258 0.257 0.257 0.257 0.257 0.540 0.876 0.539 0.873 0.259 0.538 0.258 0.537 0.258 0.536 0.257 0.256 0.256 0.256 0.256 0.30 0.20 0.727 1.376 0.617 1.061 0.584 0.978 0.569 0.941 0.559 0.920 0.553 0.906 0.549 0.896 0.546 0.889 0.883 0.879 0.255 0.254 0.543 0.542 0.535 0.534 0.534 0.533 0.533 0.532 0.532 0.532 0.531 0.531 0.256 0.531 0.256 0.531 0.256 0.530 0.256 0.530 0.256 0.530 0.529 0.527 0.865 0.863 0.862 0.861 0.860 0.859 0.858 0.858 0.870 1.079 0.868 1.076 0.866 1.074 0.857 0.856 0.856 0.855 0.855 0.851 0.848 0.254 0.526 0.845 0.253 0.524 0.842 0.40 0.30 0.20 0.854 0.854 0.15 1.963 1.386 1.250 1.190 1.156 1.134 1.119 1.108 1.100 1.093 1.088 1.083 1.071 1.069 1.067 1.066 1.064 0.10 3.078 1.886 1.638 1.533 1.476 1.058 1.057 1.056 1.055 1.055 1.440 1.415 1.397 1.383 1.372 1.363 1.356 1.350 1.345 1.341 1.337 1.333 1.330 1.328 1.325 1.063 1.323 1.061 1.321 1.060 1.319 1.059 1.318 1.058 1.316 1.315 1.314 1.313 1.311 1.310 1.303 1.296 1.050 1.045 1.041 1.289 1.036 1.282 0.15 0.10 a 0.05 6.314 2.920 2.353 2.132 2.015 1.943 1.895 1.860 1.833 1.812 1.796 1.782 1.771 1.761 1.753 1.746 1.740 1.734 1.729 1.725 1.721 1.717 1.714 1.711 1.708 1.706 1.703 1.701 1.699 1.697 1.684 1.671 1.658 1.645 0.05 0.025 12.706 4.303 3.182 2.776 2.571 2.447 2.365 2.306 2.262 2.228 2.201 2.179 2.160 2.145 2.131 2.120 2.110 2.101 2.093 2.086 2.080 2.074 2.069 2.064 2.060 2.056 2.052 2.048 2.045 2.042 2.021 2.000 1.980 1.960 0.025 I
Critical Values of the t-Distribution (Page 2) Critical Values of the t-Distribution V 1 2 3 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 40 60 120 ∞0 V 0.02 0.015 0.01 15.894 21.205 31.821 4.849 5.643 3.482 3.896 2.999 3.298 3.747 2.757 3.003 3.365 2.612 2.517 2.449 2.398 2.359 2.328 2.303 2.282 2.264 2.249 2.235 2.224 2.214 2.205 2.197 2.189 2.183 2.177 2.172 2.167 2.162 2.158 2.154 2.150 2.147 2.123 2.099 2.076 2.054 0.02 2.829 2.715 2.634 2.574 2.527 2.491 2.461 2.436 2.415 2.397 2.382 2.368 2.356 2.346 2.336 2.296 2.291 2.286 2.282 2.278 6.965 4.541 2.250 2.223 3.143 2.998 2.896 2.821 2.764 2.328 2.518 2.320 2.508 2.313 2.500 2.307 2.492 2.301 2.485 2.718 2.681 2.650 2.624 2.602 2.583 2.567 2.552 2.539 2.528 2.479 2.473 2.467 2.462 2.457 2.423 2.390 2.196 2.358 2.170 2.326 0.015 0.01 0.0075 42.433 8.073 5.047 4.088 3.634 3.372 3.203 3.085 2.998 2.932 2.879 2.836 2.801 2.771 2.746 2.724 2.706 2.689 2.674 2.661 2.649 2.639 2.629 2.620 2.612 2.605 2.598 2.592 2.586 2.581 2.542 2.504 2.468 2.432 0.0075 0.005 63.656 9.925 5.841 4.604 4.032 3.707 3.499 3.355 3.250 3.169 3.106 3.055 3.012 2.977 2.947 2.921 2.898 2.878 2.861 2.845 2.831 2.819 2.807 2.797 2.787 2.779 2.771 2.763 2.756 2.750 2.704 2.660 2.617 2.576 0.005 0.0025 127.321 14.089 7.453 5.598 4.773 4.317 4.029 3.833 3.690 3.581 3.497 3.428 3.372 3.326 3.286 3.252 3.222 3.197 3.174 3.153 3.135 3.119 3.104 3.091 3.078 3.067 3.057 3.047 3.038 3.030 2.971 2.915 2.860 2.807 0.0025 0.0005 636.578 31.600 12.924 8.610 6.869 5.959 5.408 5.041 4.781 4.587 4.437 4.318 4.221 4.140 4.073 4.015 3.965 3.922 3.883 3.850 3.819 3.792 3.768 3.745 3.725 3.707 3.689 3.674 3.660 3.646 3.551 3.460 3.373 3.290 0.0005