7. what would be the correct null-hypothesis? (hint read end of lecture 24) (5 points) a. average annual number of tornadoes occurred until 1970 (inclusive) and average annual number of tornadoes occurred after 1970 are different. b. average annual number of tornadoes occurred until 1970 (inclusive) and average annual number of tornadoes occurred after 1970 are equal. c. average annual number of tornadoes occurred until 1970 (inclusive) and average annual number of tornadoes occurred after 1970 are related. d. average annual number of tornadoes occurred until 1970 (inclusive) and average annual number of tornadoes occurred after 1970 are not related.

The correct answer is d. average annual number of tornadoes occurred until 1970 (inclusive) and average annual number of tornadoes occurred after 1970 are not related.

Explanation:

The purpose of a null hypothesis is to demonstrate that there is no statistical variation between two variables, or that one variable is not different from its mean.

A null hypothesis is taken as true until there is evidence that discredits it, thus giving rise to an alternative hypothesis, which is accepted as soon as the first one is annulled, and vice versa.

In other words, a null hypothesis is the one that proposes that two variables have nothing to do with each other, but rather it is more a matter of chance.

by: nita twenty thousand leagues under the sea some time ago, i decided to read twenty thousand leagues under the sea, by jules verne. i figured that because it was so well known it must be an extremely interesting book. in addition, it was science fiction, the one area that i was always interested. my assumption was only partially correct, for i only was to a degree interested in the piece of writing. when jules verne was writing this book, he must have been reading some incredibly dull science book the day before, for that was what the book was written as.  

the style of writing was utterly against my tastes, and though the plot was moderately interesting, the style of writing really ruined it. often, the author will trail off describing some marine animal for pages at a time. two entire chapters were almost entirely this! however, the setting and characters of the story seemed to be well thought out. nevertheless, 20,000 leagues under the sea was an extremely tedious volume. when the story was introduced, jules verne described m. aronnax, the main character, whose love for marine biology was more important than anything else to him did.  

this immediately led to the international crisis about a bizarre aquatic creature, which immediately dragged m. aronnax into the action. due to his expertise on the matter, the public expected pierre to be the one to solve this mystery. m. aronnax, under all this pressure, concluded that the animal was to be called the narwhale. at first, the matter was taken lightly, and only expert scientists were involved. however, when this animal began to become a threat to all ships in the water, the military took the issue into its own hands.  

it promptly fitted a frigate, the abraham lincoln, to destroy the beast, and invited pierre to join them, for his science capabilities. for many months they searched, but could not find this narwhale anywhere. when they found it, it attacked the ship, disabling it, and sending m. aronnax, ned land (a harpooner) and conseil (servant of pierre) overboard. soon, the three were guests in the narwhale, now known to be a ship, the nautilus, commanded by captain nemo. during the stay aboard the nautilus, pierre conseil and ned encounter and discover many wonderful and interesting facts from the sea. often, they would accompany the captain in an under water expedition.  

several of these excursions were to hunt, and others were simply to explore a submarine region. one of the times when the purpose was just to investigate an underwater region, captain nemo and m. aronnax explored the lost city of atlantis. on a separate occasion, pierre found that there was a supply of coal underwater that the nautilus used as a source of fuel. in addition to underwater excursions, the nautilus itself was on a round the world journey, which accounted for the most exiting time of the book. this was when captain nemo was attempting to access the south pole.  

that meant passing the great ice barrier, and surviving with very little air. during this rather long voyage, the submarine gets wedged between two icebergs, and is almost crushed! to add to this, the inhabitants of the nautilus almost die of suffocation from the lack of air. finally, at the end of the book, the three friends narrowly escape that nautilus.  

this all occurs during the maelstrom, which is a deadly storm, which makes the escape so daring. at the end, the three friends end up in a fisherman's shack, not knowing how they arrived, for they were knocked unconscious. that is how the events in the story twenty thousand leagues under the sea took place. the main character in this book was an extremely well recognized marine biologist named m. pierre aronnax. m. aronnax is one who gets the most benefit throughout the course of the book. pierre was always curious, which often got in the way of following his instincts and good judgment.  

also, he sometimes talked to himself! in addition, his faithful servant, conseil, follows his master during all of his adventures. conseil never really said much, and the role he played was one of a calm and humble person. another character of importance was ned land, the most well known harpooner of all his time. this man proved himself to be very useful when the threesome attempt to escape the nautilus. on the other hand, ned land was always quick tempered, and free willed.  

these qualities almost got many people killed many times during the book. the next most important character and perhaps the most outlandish one of all was captain nemo. note that this was not his real name, however, the actual name was never given in the book. captain nemo was forever strict and secretive to everyone. he never showed any emotion on his face, and never showed any bodily expressions in any way except when he was in extreme anguish. the setting that the story took place in was quite interesting.  

explanation:

i believe the answer is a