Year 12s: what will be the first way you research your future options? >>

Year 12s: what will be the first way you research your future options? >>

Year 12s: what will be the first way you research your future options? >>

Missing Mean Questions

Really don’t understand these could someone explain the steps and go through the question?

After measuring the heights of 7 people, they have an average height of 156cm. After measuring the heights of 8 people they have an average height of 158cm. How tall is the 8th person?

You need to reverse-engineer it to work out the “total” height (ie the heights of all the people added together) for the 7 people group AND for the 8 people group.

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Original post by princesslishi

Really don’t understand these could someone explain the steps and go through the question?

After measuring the heights of 7 people, they have an average height of 156cm. After measuring the heights of 8 people they have an average height of 158cm. How tall is the 8th person?

If you say the total height of 7 people is

A

, then we have

\dfrac{A}{7}=156

.

If you say the height of the 8th person is

x

(so that

A+x

represents the total height of 7 people + the 8th, hence 8 people), then we have

\dfrac{A+x}{8}=158

We have sufficient information to determine what we're looking for.

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