For each of the following, indicate if the answer has a positive or negative sign: Two negative numbers are added.

Classify the following statements as an observation (O) or a hypothesis (H): The 100-yd dash was run in 9.8 s.

Classify the following statements as an observation (O) or a hypothesis (H): Dinosaurs became extinct when a large meteorite struck the Earth and caused a huge dust cloud that severely decreased the amount of light reaching the Earth.

Classify the following statements as an observation (O) or a hypothesis (H): A patient breaks out in hives after receiving penicillin.

If the toxic quantity is $1.5$ g of ethylene glycol per $1000$ g of body mass, what percentage of ethylene glycol is fatal?

According to Sherlock Holmes, "One must follow the rules of scientific inquiry, gathering, observing, and testing data, then formulating, modifying, and rejecting hypothesis, until only one remains." Did Holmes use the scientific method? Why or why not?

A container was found in the home of the victim that con- tained $120$ g of ethylene glycol in $450$ g of liquid. What was the percentage of ethylene glycol? Express your answer to the ones place.

A "chemical-free" shampoo includes the following ingredients: water, cocomide, glycerin, and citric acid. Is the shampoo truly "chemical-free"?

A "chemical-free" sunscreen includes the following ingredi- ents: titanium dioxide, vitamin $E$, and vitamin $C$. Is the sun- screen truly "chemical-free"?

In A Scandal in Bohemia, Sherlock Holmes receives a mysterious note. He states, “I have no data yet. It is a capital mistake to theorize before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts.” What do you think Holmes meant?

Identify the following as an observation (O), a hypothesis (H), an experiment (E), or a conclusion (C): Sally realizes that she does not have an allergy to shrimp.

According to Sherlock Holmes, “One must follow the rules of scientific inquiry, gathering, observing, and testing data, then formulating, modifying, and rejecting hypotheses, until only one remains.” Did Holmes use the scientific method? Why or why not?

Identify the following as an observation (O), a hypothesis (H), an experiment (E), or a conclusion (C): Today, Sally had some soup that contained shrimp, but she did not break out in hives.

Identify the following as an observation (O), a hypothesis (H), an experiment (E), or a conclusion (C): Yesterday, one hour after Sally ate a shrimp salad, she broke out in hives.