This may seem elementary! But my handbook gives another answer that I get.

Rivets are placed 35.2 millimetres apart. If 28 rivets are placed in an assembly, calculate the distance between the first and last rivets.

There would be 27 intervals between the 1st and last rivet.

27 X 35.2 = 950.4mm

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He who knows not and knows not that he knows not is a fool, shun him. He who knows not and knows that he knows not is a child, teach him. He who knows and knows not that he knows is asleep, wake him. And he who knows and knows that he knows is wise, follow him.
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Thank you! This is what my book also say. But this phrase “calculate the distance between” .. tells me to exclude the first and the last rivet and therefore I get (28 – 2) x 35.2 = 915.2. .... ?

You are looking at the intervals between the rivets and not the rivets themselves. There will always be one less interval (space between rivets) than the number of rivets. And it is the space that is 35.2 mm in length. And you have 27 of them.

Example:



X = rivet

You have 5 rivets and 4 intervals (spaces between the Xs).

__________________
He who knows not and knows not that he knows not is a fool, shun him. He who knows not and knows that he knows not is a child, teach him. He who knows and knows not that he knows is asleep, wake him. And he who knows and knows that he knows is wise, follow him.
-- Persian Proverb

Rite masters is rite, consider it like this, you have 28 rivets, and each one should have 35.2 millimeters in front of it before the next rivet, so logically, you would think 28*35.2, HOWEVER, you don't include the distance after the last one because there isnt another rivit after it.

So you have 27 instead, then u have 27*35.2= 950.4 , this is the right answer.

Hope this helped.