電大社會(huì)統(tǒng)計(jì)學(xué)期末考前通關(guān)復(fù)習(xí)題參考資料-在線瀏覽
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【正文】 6 7 8 9 10 160 161 165 165 167 170 172 174 176 180 51 56 59 66 63 70 69 73 80 65 某工廠 50 名職工每天工資數(shù)分配情況如下表，試求 ：（ 1）眾數(shù)所在的組；（ 2）中位數(shù)；（ 3）平均數(shù)。 歸屬感（ Y） 工作滿(mǎn)意度（ X） Fy 低（ 1） 中（ 2） 高（ 3） 低（ 1） 8 4 3 15 中（ 2） 6 5 1 12 高（ 3） 4 4 5 13 Fx 18 13 9 40 1在一個(gè)正態(tài)總體中抽取一個(gè)容量為 25 的樣本，其均值等于 52，標(biāo)準(zhǔn)差 S=12，求置信水平為95%的總體均值的置信區(qū)間。研究者懷疑屬于干部和知識(shí)分子的家庭抽得 過(guò)多。問(wèn)：該研究人員是否有理由懷疑該樣本有偏估？（選用α =） 1設(shè) x 為一般正態(tài)分布的變量，請(qǐng)計(jì)算： （ 1） (x )rp ＞ ，如果 x =5， S=2； （ 2） (x 860)rp ＜ ，如果 x =500， S=300； （ 3） ( )rpZ＜ ＜ ，如果 x =10， S=； （ 4） (10 )rpZ＜ ＜ 11，如果 x =， S=。 調(diào)查對(duì)象 X（受教育年限） Y（職業(yè)聲望） XY X2 1 12 70 2 16 80 3 9 50 4 19 86 5 21 90 6 10 65 7 5 44 8 12 75 總數(shù) (∑ ) 1為了驗(yàn)證統(tǒng)計(jì)報(bào)表的正確性，作了共 50 人的抽樣調(diào)查，人均收入結(jié)果有： ?X=871 元， S=21 元，問(wèn)能否證明統(tǒng)計(jì)報(bào)表中人均收入 ?=880 元是正確的 (顯著性水平 ?=)。 請(qǐng) 您刪除一下內(nèi)容， O(∩ _∩ )O 謝謝?。?！ 2021 年中央電大期末復(fù)習(xí)考試小抄大全，電大期末考試必備小抄，電大考試必過(guò)小抄Acetylcholine is a neurotransmitter released from nerve endings (terminals) in both the peripheral and the central nervous systems. It is synthesized within the nerve terminal from choline, taken up from the tissue fluid into the nerve ending by a specialized transport mechanism. The enzyme necessary for this synthesis is formed in the nerve cell body and passes down the axon to its end, carried in the axoplasmic flow, the slow movement of intracellular substance (cytoplasm). Acetylcholine is stored in the nerve terminal, sequestered in small vesicles awaiting release. When a nerve action potential reaches and invades the nerve terminal, a shower of acetylcholine vesicles is released into the junction (synapse) between the nerve terminal and the ‘effector’ cell which the nerve activates. This may be another nerve cell or a muscle or gland cell. Thus electrical signals are converted to chemical signals, allowing messages to be passed between nerve cells or between nerve cells and nonnerve cells. This process is termed ‘chemical neurotransmission’ and was first demonstrated, for nerves to the heart, by the German pharmacologist Loewi in 1921. Chemical transmission involving acetylcholine is known as ‘cholinergic’. Acetylcholine acts as a transmitter between motor nerves and the fibres of skeletal muscle at all neuromuscular junctions. At this type of synapse, the nerve terminal is closely apposed to the cell membrane of a muscle fibre at the socalled motor end plate. On release, acetylcholine acts almost instantly, to cause a sequence of chemical and physical events (starting with depolarization of the motor endplate) which cause contraction of the muscle fibre. This is exactly what is required for voluntary muscles in which a rapid response to a mand is required. The action of acetylcholine is terminated rapidly, in around 10 milliseconds。 in response to activation of this nerve supply, smooth muscle contracts (notably in the gut), the frequency of heart beat is slowed, and glands secrete. Acetylcholine is also an important transmitter at many sites in the brain at nervetonerve synapses. To understand how acetylcholine brings about a variety of effects in different cells it is necessary to understand membrane receptors. In postsynaptic membranes (those of the cells on which the nerve fibres terminate) there are many different sorts of receptors and some are receptors for acetylcholine. These are protein molecules that react specifically with acetylcholine in a reversible fashion. It is the plex of receptor bined with acetylcholine which brings about a biophysical reaction, resulting in the response from the receptive cell. Two major types of acetylcholine receptors exist in the membranes of cells. The type in skeletal muscle is known as ‘nicotinic’。 and there are some of each type in the brain. These terms are used because nicotine mimics the action of acetylchol
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