1. 
Seafloor rocks from a secret area above the Arctic Circle were recently analyzed by ZGlobe. The company had a contract with Spacegov.biz to test the rocks for nickel. ZGlobe found that seven samples from the first location were composed of an average of 9.16% nickel. Nine samples from the second location yielded an average of 6.88% nickel. What was the overall average nickel content of the rock samples? Round your answer to the nearest hundredth. (Remember it is not the average of the two averages.)


2. 
Christian is determining the solubility of the new organic compound he has made in the lab. It was not very soluble in water so he is trying it in methanol. He kept adding small amounts of the golden colored powder to fifty ml of methanol until no more dissolved. In fact there was still a little left undissolved in the flask, so he must have actually went past the saturation point. He had added 0.35 g of the compound. He then added three more ml of methanol, which was just enough to completely dissolve the remainder of the compound. So, what is his result for the saturation point (in g/ml) for the new compound in methanol? Round your answer to the nearest tenthousandth. __________ g/ml


3. 
During a geological survey by ZGlobe Corporation, a particular parcel of land was found to consist of alternating layers of sand and clay. The thickness of the first clay layer was about 43.9 cm and the second one was about 75.6 cm. There was a layer of sand in between the two clay layers. If the total thickness of the three layers (claysandclay) was about 171 cm, what percent of the total thickness was made up of sand? Round your answer to the nearest hundredth.


4. 
* This is a premade sheet. Use the link at the top of the page for a printable page. 

5. 
You do an experiment to collect data on earthworm behavior. You test the hypothesis that "If a worm is put into a terrarium, it will begin to bury itself within 10 seconds." After analyzing the data you report that the probability that a worm will begin to bury itself within 10 seconds is 0.83. Based on this information, what is the probability that the next two worms in a row will "bury within 10 seconds?"


6. 
There is a rift about 12 km west of Seaside. Scientists have been measuring the depth of the rift for over a decade now and report that it gets deeper by an average of 8.4 cm per year. If the rift was 6.9 cm deeper last year, by what percent did the depth change differ from the annual average? Round your answer to the nearest hundredth.

