Question

What z score separates the bottom 21% of the distribution from the rest of the distribution?

- 0.5

+0.5

- 0.8

+0.8

Dr. Kelly predicted students in his evening classes slept fewer hours per week than students in his morning classes. The hypothesis specified is called a __________ hypothesis and the critical region is ________.

Two tailed, split between the two tails of the distribution

One tailed; concentrated in one tail of the distribution

Bi-directional, concentrated in one tail of the distribution

One-tailed; split between both tails of the distribution

Answer 1

We need to find z such that $P(Z<z)=0.21$

So $P(z<-0.8)=0.21$

So answer here is z=-0.8

0.00 0 0.02 003 0.04 085 0.06 0.7 0 % 0.00 3. 0.003 0.00 0.0003 .0003 0.00 0.0003 0.0003 0.003 0.0000 0.0002 0. 005 0.005 0.005 004 0004 0.0004 0.004 0.0004 0.0004 0.000.3 J20007 007 0.0CM CONCE OCG 60006 0.006 00005 065 6 65 - 3 0w 10 0.009 0.00 CM 2008 00006 0.00 00006 10007 0.007 3.0 0.0013 0.2013 0.0013 0.0012 2012 0.0011 0.00 11 0.0011 0.00 10 0.0010 | 0.00 19 0.00 16 0.00 16 0.0017 2016 0.001 0.005 0.0015 0.004 0.0014 0.0026 0.025 0.024 102 04023 0.0022 0.0021 0.021 0.0020 0.019 -2. 7 0.00 35 0.0034 0.0003 0.00次 0.031 0.0030 0.00 0.0026 0.0027 0.0026 -26 00047 a0045 0.00 44 4.0043 0 041 0.00 0.009 0038 0.0037 0.0036 | 0006 0.000 0.0059 0.005 005 0.0054 0.002 00051 0.004 0.0046 0.0022 0.00 0.0070 0.0075 0.003 0.0071 0.00 0 0.0000 0.0066 0.0064 -2.3 0.0107 0.0104 0.0102 0.0093 0.4096 0.0094 0.001 0.0089 0.0067 0.0084 22 00139 0.01 36 0.0132 00129 0.0125 0.0122 0.019 00116 0.01 13 00110 2.1 0.019 0.174 0.0470 0.01 20162 0.0158 0.014 0.0150 0.014 0.0143 42.0 0.0226 0.0222 0.0217 0.0212 00207 0.0202 0.0197 00192 0.01 00143 -1.9 00287 0.0261 0.0274 0.0266 0.0262 0.0256 0.025 0.0244 0.029 00233 1.8 0.0359 0.0351 0.034 0.0336 0.0329 0.0322 0.0314 0.0307 0.0301 0.0294 0.0446 0.0436 0.0427 0.0418 0.049 0.0401 0.0392 0.0384 0.0375 0.0367 1.1 0.0546 0.0537 0.0526 0.05 16 0.0505 0.0495 0.04 0.0475 0.0465 0.0455 -1.5 0.0668 0.0655 0.0643 0.0630 0.9619 0.0606 0.059 0.0592 0.0571 0.0559 - 1.4 0.0806 0.0793 0.0778 0.074 0.079 .0735 0.0721 0.0708 0.0694 0.0641 -1.3 00966 0.0951 0.0934 0.0918 0 1901 .0635 0.00的 006530830 0.0673 10.1151 0.1131 0.1112 0.1003 0.1075 0.105% 0.1031 0.1020 9.1003 0.0015 1. 1 0.1357 0.1335 0.1314 0.1292 0.1271 0.1251 0.1230 01210 0.1 0.1170 - 1.0 0.1587 0.1562 0.15.39 0.1515 0.142 4.14162 0.1440 0.1423 0.1401 0.1379 -0. 1441 1814 0.1786 17R 0.1736 1711 0.7665 01660 0.1635 0.1611 | 0 21 11 0.00 02061 6203 02005 197 0.1949 01922 0.184 0.167 | 02420 0.2389 02358 0.2327 02256 0226 023 02206 0217 02148 0.6 02743 0.279 0.2676 0.2543 0261 2578 0.2546 02514 0.2483 02451 5 03035 0.50 0.3015 0.29% 0% 07-12 487 02843 02 10 02776 103446 0.4的 03372 0.336 03300 03264 03228 03192 0.315 03121 03 03621 0.37 0.3745 0.3702 03 0.3632 0.3594 03557 23520 0.34 02 0.4207 0.418 0.4129 0.4092 0.4052 0.42 13 0.974 0.3936 0.49 0.3899 -0.11 0 4602 0.4562 0.4522 0.43 043 04404 0.438 04325 0428 0.4247 40 05000 0.4960 0.4920 0.480 0.4840 0.4501 0.4761 04721 0.4681 0.4641

Here claim is that  evening classes slept fewer hours per week than students in his morning classes.

So it is one tailed test

Hence answer is

One tailed; concentrated in one tail of the distribution