







Predicting the number of fish in a lake 
20180916 

From April: A researcher catches 30 fish in a pond, attaches a marker to their fin and releases them. The next day she places a large net in the water and catches 9 fish. 3 have the marker attached to their fin. Can she predict the number of fish in the pond???
Thank you Answered by Penny Nom. 





How much does the fish weigh? 
20170308 

From Jeri: Fish is caught that weighs 5 pounds plus half its weight. How much does the fish weigh? Answered by Penny Nom. 





A fishfinder 
20150313 

From Dave: I have a fishfinder that has a 20 degree cone on bottom of boat going to the bottom of the lake.
How do I know the size of base diameter of the cone on the lake bottom depending on depth...
such as 10 feet deep, for example? Answered by Penny Nom. 





Eleven guys on a fishing trip 
20140513 

From Mark: Eleven guys are going on a fishing trip and want to rotate so everyone fishes with the other guys with the fewest number of repeats.
They want to fish in groups of two with one fishing alone for
three and a half days so will rotate seven times.
Is there a combination that works and what is it? Answered by Victoria West. 





A cone of vision 
20140429 

From David: It is known that a fish in water looking up has a 97 degree "cone" of vision that sees "through" the surface of the water. If a fish lies 4 inches below the surface, the cone forms a window (circle) smaller than if a fish lies 8 inches below the surface. What is the ratio of inches of depth to the radius of the circle on the surface that is its visual window? Answered by Penny Nom. 





Scheduling a 12 person fishing 
20130709 

From Don: Greetings Math Central!
I searched the index, but could not find a similar quandary.
Here's my predicament:
I am seeking help in scheduling a 12 person fishing outing.
We have four boats.
I would like to schedule three fishermen to a boat.
We fish 2 1/2 days, split into morning and afternoon sessions.
Thursday afternoon, Friday morning, Friday afternoon, Saturday morning, and
Saturday afternoon
We switch boats after lunch, with each fisherman moving to a different boat,
with different partners.
I would like to have each fisherman fish with as many others in the group as
possible, with a minimum of partner duplication.
I would like to have each fisherman fish in all of the four different boats
over the course of the trip at least once.
Would you please suggest a boat / fishing partner schedule that fits my
parameters as closely as possible.
Thank you!
Don Answered by Victoria West. 





3 fish 
20111027 

From Ann: You have 3 fish weighing a total of 21 lbs. The largest fish weighs twice as much as the second fish and the third fish weighs half the amount of the second fish.
So how much does the third fish weigh? Answered by Penny Nom. 





A degreaser for a fish tank 
20090723 

From charlie: I have a tank that is 10 feet in diameter that I want to put floating degreaser in.The rate for the degreaser is 1/2 gallon per square foot of surface water.How do I figure out how many gallons I need? Answered by Penny Nom. 





Fish in a pond 
20080628 

From Peter: At the beginning of a study 24 fish are caught, tagged, and released back into a large pond containing fish. A few days later, 19 fish are caught from the pond and three of them have tags. Using this ratio, how many total fish would you expect to be living in the pond?
The answer is 152. Why is that? Answered by Leeanne Boehm. 





How may litres are in my fish pond 
20070318 

From beryl: I need to work how may litres in my fish pond.
I have measures it in two sections because of it shape.
One section is 1600w, 1100L, 540D.
the other section is 1060W, 1800L, 380D.
Thank you
beryl Answered by Penny Nom. 





The capacity of our hexagon fish tank 
20060726 

From Doug and Andrea: My name is Andrea and my son, Doug, and I were wondering what the capacity of our hexagon fish tank was but it’s been so long since I’ve been to school that I’ve forgotten the formula to do so. Would you please help us? The dimensions are: 27 ¾ W x 24L x 29H or one side (glass panel) is 14W x 29H. Answered by Penny Nom. 





Trading fish for bread 
20050225 

From Mike: Byron lives where people trade goods they produce for other things they
need. He has some fish and wants to trade them for bananas. He finds
the following:
5 fish = 2 loaves of bread
6 oranges = 2 melons
1 loaf of bread = 1 banana and 3 oranges
4 loaves of bread = 14 oranges
How many bananas can Byron get with 5 fish? Answered by Penny Nom. 





Constructing a cone 
20040907 

From Steve: I am trying to build crayfish traps; one of the components is a cone shaped entry section.
The cone I want to make would be 12" in diameter at the base and 12" in height, from base to peak.
I need a formula to calculate the dimensions and a method of transferring the shape onto a flat piece of material.
Answered by Harley Weston. 





A fish tank 
20031126 

From Bill: How do I work out the volume and weight of water in a fish tank that is 36in x 14in x 12in? Answered by Penny Nom. 





The volume of a fuel tank 
20030816 

From Phil: I hope you can help me out with a small problem. My boat has a fuel tank measuring 1680mm long x 630mm wide x 130mm high. Can you tell me how much fuel it will hold in both litres and imperial gallons. Answered by Penny Nom. 





The weight of a fish tank 
20030520 

From A ponderer: I had a question pertaining conversion units..I have a fish tank at home and the dimensions are 24, 44, and 48 inches, I want to find out how much it weighs in pounds when filled up with water...knowing water is 62.4 pounds per cubic feet...do I just divide the 62.4 pounds to 12 because I"m trying to find out through cubic inches. Answered by Penny Nom. 





Working backwards 
20030314 

From Melody: Triva went to the ardcade at the state fair to win some goldfish. She already had some goldfish at home, but wanted more. She won enough goldfish to double her stock. Her mom made her give four away. She put her new ones in the tank with the others, by the morning half of the goldfish had died. Triva's friend gave her six more. The next morning twothirds of her goldfish died. She was left with two goldfish after giving one to a friend. How many goldfish did she start with? Answered by Penny Nom. 





A fish weighs 10 pounds more than half its weight. 
20020910 

From Rebecca: A fish weighs 10 pounds more than half its weight. How much does it weigh? Answered by Penny Nom. 





Three goldfish 
20010530 

From Nathan: A man has three goldfish. When the youngest goldfish was born, the oldest fish was three times the middle fish's age. Nine years ago the oldest fish's age was the sum of the two other fish's ages. How old are the three goldfish? Answered by Penny Nom. 

