After Albemarle's heat wave, the rest of June was cooler. In fact, at the end of the month, meteorologists reported that the average high for all 30 days in June was just $80^/circ$ (degrees Fahrenheit). What was the average high (in degrees Fahrenheit) from June 11 through June 30?

The question was incomplete. Here is the complete question:

The "normal" high temperature for a June day in Albemarle is 82 degrees (degrees Fahrenheit).

Last year, the first ten days of June were unusually hot, with highs of 84 degrees, 88 degrees, 91 degrees, 92 degrees, 96 degrees, 94 degrees, 89 degrees, 78 degrees, 87 degrees and 81 degrees.

(a) How many degrees above normal was the average high for that 10-day period?

After Albemarle's heat wave, the rest of June was cooler. In fact, at the end of the month, meteorologists reported that the average high for all 30 days in June was just 80 degrees.

(b) What was the average high (in degrees Fahrenheit) from June 11 through June 30?

Answer:

(a) 6° above average

(b) 76°

Step-by-step explanation:

(a) First we need to find the average of the high temperatures for the 10 days:

(84 + 88 + 91 + 92 + 96 + 94 + 89 + 78 + 87 + 81) / 10

= 880/10

= 88°

from question we know "normal" high temperature for a June day in Albemarle is 82°

so 88° - 82° = 6° is above normal

(b) If average for 30 days is 80° then the sum of all temperatures for 30 days = 30*80

= 2400

For the first 10 days the sum of temperatures = 880 as computed above. So the sum of temperature for the remaining 20 days is

2400 - 880 = 1520

The average for last 20 days is

1520/20

= 76° (average high (in degrees Fahrenheit) from June 11 through June 30)