Question

The average temperature across a week in December in the city of Yakutsk is –30 °C. If Friday was colder than Saturday by 10 °C, find the temperatures on Friday and Saturday.

• A. Friday (–36 °C); Saturday (–26 °C)
• B. Friday (–35 °C); Saturday (–25 °C)
• C. Friday (–37 °C); Saturday (–27 °C)
• D. Friday (–34 °C); Saturday (–24 °C)

Answer 1

The correct option is C Friday (–37 °C); Saturday (–27 °C)

$TemperatureonFriday=FTemperatureonSaturday=S$

Calculating the average, we get:

$Average=\frac{–28–30–31–28–29+F+S}{7}=\frac{–146+F+S}{7}$

As we know, the average temperature across the week is –30 °C.

$⟹\frac{–146+F+S}{7}=–30⟹–146+F+S=–210⟹F+S=–64$

We also know that Friday was colder than Saturday by 10 °C.

$⟹F=S–10$

Combining the equations, we get:

$F+S=–64⟹(S–10)+S=–64⟹2S=–54⟹S=–27$

Also,

$F=S–10=–27–10=–37$

Hence, the temperatures on Friday and Saturday are:

$Friday⟹–37°CSaturday⟹–27°C$