created 08/01/99; edited 06/09/2015
Write a program that calculates the annual cost of running an appliance. The program asks the user for the cost per kilowatt-hour and the number of kilowatt-hours the appliance uses in a year:
Enter cost per kilowatt-hour in cents 8.42 Enter kilowatt-hours used per year 653 Annual cost: 54.9826
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When a brick is dropped from a tower, it falls faster and faster until it hits the earth. The distance it travels is given by
d = (1/2)gt2
Here d is in feet, t is the time in seconds, and g is 32.174. Write a program that asks the user for the number of seconds and then prints out the distance traveled.
Enter the number of seconds: 5.4 Distance: 469.096
Use the program to determine how far a brick falls in 100 seconds.
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The base 2 logarithm of a number is defined by:
log2 X = n if 2n = X
For example
log2 32 = 5, because 25 = 32
log2 1024 = 10, because 210 = 1024
Write a program that inputs a number and outputs its base 2 logarithm. Use floating point input. This problem would be easy, but the Math package does not have a base 2 logarithm method. Instead you have to do this:
log2 X = (loge X) / (loge 2)
Here, loge X
is the natural logarithm of X,
which you can compute using
Math.log( X )
As usual, X is a double
.
The user enters floating point numbers:
Enter a double: 998.65 Base 2 log of 998.65 is 9.963835330516641
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The harmonic mean of two numbers is given by:
H = 2 / ( 1/X + 1/Y )
This is sometimes more useful than the more usual average of two numbers. Write a program that inputs two numbers (as floating point) and writes out both the usual average (the arithmetic mean) and the harmonic mean.
Enter X: 12 Enter Y: 16 Arithmetic mean: 14.0 Harmonic mean: 13.714285714285715
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