Average Earnings

[harpazo]

Tracy mowed lawns for 2 hours and earned $7.40 per hour. Then she washed windows for 3 hours and earned $6.50 per hour. What were Tracy's average earnings per hour for all 5 hours?

Solution:

2(7.40) = 14.80

3(6.50) = 19.50

Let T = Tracy's average earnings for all 5 hours.

T = (14.80 + 19.50)/5

T = 34.30/5

T = 10.76

Correct?

 

[Otis]

... What were Tracy's average earnings per hour for all 5 hours? ...

34.30/5 = 10.76

Correct?

No. 34.30/5 = 6.86

We know that 5×10 is 50 (which is way more than 34.3), so we can recognize that 10.76 must be incorrect.

(The rest of your work looks good.)

Note: It's good form to answer word problems with a complete sentence (including units).

EG: \(\;\) "Tracy's average earnings for all 5 hours was $6.86/hr."

?

 

[tkhunny]

Tracy mowed lawns for 2 hours and earned $7.40 per hour. Then she washed windows for 3 hours and earned $6.50 per hour. What were Tracy's average earnings per hour for all 5 hours?

T = 10.76

One may also note, if we're mixing:

$6.50 < Average < $7.40

$10.76 is substantially outside the appropriate interval.

 

[harpazo]

Thank you, both. I see my mistakes.