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Word problemsArithmeticMiddle schoolabout 0:36

The average of 4, 8 and x is 7. Find x: animated lesson

A narrated, step-by-step word problems video lesson with captions. Final answer: x = 9.

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Video with a synthetic English voice and captions. Pick another language for subtitles in that language, or open the interactive version.

Video narrated by a synthetic voice (Piper TTS, en_US-ljspeech-high voice (LJ Speech dataset, public domain)); the steps come from our maths engine and the answer was checked independently. Download MP4 (0.2 MB) · Captions (WebVTT)

Steps on screen

1. The problem
Worked example
The average of 4, 8 and x is 7. Find x.
2. Step by step
1. Total needed
2. Solve for x
3. The answer
$\text{x = 9}$
x = 9
4. Check
- (4 + 8 + 9) / 3 = 7 ✓

Transcript

The problem. Here is the problem: The average of 4, 8 and x is 7. Find x. The mean of 4, 8 and x is 7.

Step by step. Total needed. 3 values with mean 7 sum to 3 times 7 equals 21. Solve for x. x equals 21 minus (4 plus 8) equals 21 minus 12 equals 9.

The answer. So the answer is x equals 9. The mean of 4, 8 and x is 7.

Check. (4 plus 8 plus 9) / 3 equals 7, which checks out.

About word problems

Turn everyday situations about prices, speed, ages and interest into equations and solve them.

The average of 4, 8 and x is 7. Find x: Word problems Lesson