The average of the 5 temperatures is:  $\frac{a+b+c+d+e}{5}=50$

One of these temps is 45: $\frac{a+b+c+d+45}{5}=50$.

Solving for the variables: a + b + c + d = 205

In order to find the greatest range of temps, we minimize all temps but one. Remember, though, that 45 is the lowest temp possible, so: 45 + 45 + 45 + d = 205 Solving for the variable: d = 70

70 - 45 = 25 Option (b).

2nd method:- For finding maximum range, we will take 4 days minimum out of 5 days i.e 4 days temp. will take 45, then total negative deviations will be 20. Thus for average 50, positive deviation should be also 20 . Thus highest temp will be (50+20)=70 degrees. Then range =70-45 = 25. Option (b).