3. An experiment was conducted to determine how various drop heights of ball bearings affects the diameter of the indentation. The ball bearings were 5 cm in
diameter and dropped into 250 grams of sand. The sand was contained in a pie
tin 25 cm across. Students measured the width (cm) of the crater caused by the
ball bearings falling into the sand. The height of the ball bearings was increased
by 10 cm cach time.

Volume of Box / volume of tin = number of tins required

Volume of box =50*40*20= 40000 cu.cm

Volume of Tin = pi*r^2*h=pi*4^2*15 = 754 cu.cm

4000/754= 53 tins (rounded off)

i'm sorry if this is a bit complicated but i hope it answers your question. Take care.

Explanation:

precipitation

explanation:

when it goes from cloud to rain/back to earth in the form of rain

1. the question asks the most appropriate, which seems to rule out "all of the above." your choice appears to be the correct one.

2. the protocol described is good for identifying correlation, but not cause and effect. for cause/effect, you need to devise a protocol that will assign the treatment (or not) to groups that have essentially the same "demographics" with respect to all the other variables. your choice regarding control group seems appropriate. random assignment of treatment (choice d) may be appropriate also. (i think you can argue that b and d are just different descriptions of the same method.)

3. d will randomize the birds, but may not guarantee there are 10 in each group. e will do both, so seems the better choice.

comment on question 2

based on the problem statement, it seems clear that confident, attentive drivers are more likely to use daytime running lights. so, the protocol might need to be devised in such a way that the lights would be turned on or off without the driver's knowledge. (an attentive driver will figure it out.) assigning a confident, attentive driver to a group required to drive without running lights might mess with his/her confidence and attentiveness. you don't want your experiment to do that. (nor do you want the experiment to subject a driver to greater risk of accident as a consequence of driving without running lights.) experiments involving human safety are always problematic.