Op-Amp 1 and Temperature Converter combo pack (2 blogs in 1)

An Operational amplifier is a very useful electronic piece that is used in many different applications of electrical circuit. In this lab we tried to use both amplifying and level shifting aspect of op-amps. We used a LM-741 to amplify temperature readings of the environment in 10mV/C and then do a level shift to convert this value to corresponding degree in Fahrenheit.
Following is the internal block diagram of LM-741.

Since we have to amplify the analog signals received by the temperature probe by a factor of 1.8 and also a negative output is not desired, we chose to use the non-inverting input of the circuit which is at leg 3 of the op-amp.
Below is a schematic of a simple non-inverting op-amp.

The gain in such op-amps is: A=(1+Rf/Ri)

However before approaching the temperature problem, to get a better understanding of the circuit design and operation we just tried to construct a circuit with a gain of 10. Later we used the experience to address the requirements for the temperature converter.
For the first part the design agreed on in the group was the following:

The combination of the 9k and 1k ohm resistors according to the formula should give us the gain of 10.

A=(1+9/1)=10

In this setup the left block with the 5 volt battery supply represents the sensor which in this case is just a voltage divider to ensure that the current limitation is met.
To construct the circuit these components were used:

After constructing the circuit the measurements read:

The gain error percentage for most tries is less than 5%
after this we were ready to change some values in components in order to achieve the gain of 1.8.
According to equations given, T_F=1.8T_C+32.
Translation of this formula to something achievable by circuit element is:

Where 1+R2/R1 is the gain which has to be equal to 1.8. VC is the output voltage of AS35, the temperature probe, also input of the non-inverting op-amp. Vref is chosen in a way that after multiplying by R2/R1 result would be 32.
We kept our R2 as 1k ohm as a result to get a ratio of 0.8 from R2/R1,  R2 had to be 800 ohm.
As for the Vref we used 0.4V since 0.4*0.8 gave us 0.32.

To gain the 800 ohm resistance we used a resistor box.  

the room temperature was about 23 degrees and reading on the meter showed 0.71

which corresponds to the 72 degree Fahrenheit.