Question

Students are selling magnets. One magnet is $0.20, two magnets is $0.38, three magnets is $0.56, and four magnets is $0.74. If this pattern continues how much will six magnets cost?

Answer 1

The cost of six magnets is $1.10

Explanation:

The cost of 1 magnet = $ 0.20

Cost of 2 Magnets = $ 0.38

Now, the series of the cost of magnets is:

0.20 , 0.38, 0.56 , 0.74,...

Now, the above series forms an Arithmetic Progression as

0. 38 - 0. 20 = 0.18

and 0. 56 - 0. 38 = 0.18

Hence, the common difference of the series = 0.18

and first term of the series = 0.20

By , A.P a(n) = a + (n-1) d

⇒
`a_6 = 0.20 + (6-1)(0.18)  \implies  a_6 = 0.20 + 5(0.18)`

or, a(6) = 0.20 + 0.9 = 1.1

or, the sixth term in the sequence is $1.1

Hence, the cost of six magnets is $1.1