Question

student handout: unit 3 lesson 4
celsius
fahrenheit
some important temperatures
69°f = 19°c (room temperature)
75°f = 25°c
85°f = 32°c
32°f = 0°c (freezing point of water)
practice
convert each of the following:
use the thermometer to complete the table:
temperature in °c 10 22
temperature in °f -10 90 0

Explanation:

Step1: Recall conversion formula

The formula to convert Celsius ($C$) to Fahrenheit ($F$) is $F=\frac{9}{5}C + 32$, and to convert Fahrenheit to Celsius is $C=\frac{5}{9}(F - 32)$.

Step2: Convert $10^{\circ}C$ to $^{\circ}F$

Substitute $C = 10$ into $F=\frac{9}{5}C+32$. So $F=\frac{9}{5}\times10 + 32=18 + 32=50^{\circ}F$.

Step3: Convert $- 10^{\circ}F$ to $^{\circ}C$

Substitute $F=-10$ into $C=\frac{5}{9}(F - 32)$. Then $C=\frac{5}{9}(-10 - 32)=\frac{5}{9}\times(-42)=-\frac{70}{3}\approx - 23.3^{\circ}C$.

Step4: Convert $90^{\circ}F$ to $^{\circ}C$

Substitute $F = 90$ into $C=\frac{5}{9}(F - 32)$. So $C=\frac{5}{9}(90 - 32)=\frac{5}{9}\times58=\frac{290}{9}\approx32.2^{\circ}C$.

Step5: Convert $22^{\circ}C$ to $^{\circ}F$

Substitute $C = 22$ into $F=\frac{9}{5}C+32$. Then $F=\frac{9}{5}\times22+32=\frac{198}{5}+32 = 39.6+32=71.6^{\circ}F$.

Step6: Convert $0^{\circ}F$ to $^{\circ}C$

Substitute $F = 0$ into $C=\frac{5}{9}(F - 32)$. So $C=\frac{5}{9}(0 - 32)=-\frac{160}{9}\approx - 17.8^{\circ}C$.

Answer:

Temperature in $^{\circ}C$	10	- 23.3	32.2	22	- 17.8