PreAlgebra: Video introduction to Transformations of the coordinate plane

 https://www.youtube.com/watch?v=jFPqnFxyEek

Transformations on the coordinate plane.

Pre-Algebra Q2 Temperature change from minus to more minus

 The temperature on a winter Monday morning is -15.4 degrees according to a digital thermometer.  The temperature drops a little more each day.  Four days later, it has dropped 20% from the Monday morning reading of -15.4.  What is that temperature four days later after the 20% drop, measured to the tenth of a degree?

Explain in writing how you completed the task.  What did you do and in what order did you do it?

After you have completed your written explanation, pick a new starting temperature for a new problem.  Please choose a negative temperature between -1 and -9.  Then choose a percentage drop of between 20% and 40%.  After you set up the new problem, solve it yourself and be prepared to explain your problem and answer.  

Something to think about...

If we started at +10 degrees and had a 50% drop, would you expect the new temperature to be +5 degrees?  If we started at -10 degrees and had a 50% drop, would you expect the new temperature to be -5 or -15?  Why?

An answer and explanation for Q2 will be published in another post soon.

Pre-Algebra A1 Answer for filling the tank

The cost of gas for a truck is $3.59.  The gas tank holds 28.2 gallons when empty, but it is 1/5 full now.  How much will it cost to fill the tank?

Answer:  $80.99   (80.9904 rounded to cents)

The tank needs 22.56 gallons to become full (80% of 28.2, because 1/5 is 20%).  Now multiply $3.59 times 22.56.

An alternate method would be to calculate the cost of a full tank, then subtract 20%.  The full tank ($3.59 times 28.2) is $101.238; do not round in the middle of the task.  20% of $101.238 is $20.2476.  Subtract $20.2476 from $101.238 and you get $80.9904.