Arithmetic Sequence: Finding Weekly $5 Price Increases from $20 Base Price

Question

Peter buys a shirt for 20 dollars.

Each week its price increases by 5 dollars.

Choose the appropriate sequence to represent the price of the shirt.

Video Solution

Solution Steps

00:00 Find the sequence that matches the shirt price
00:03 This is the initial price of the shirt
00:10 The difference between each term is 5 according to the data
00:26 And this is the solution to the question

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Identify the starting price and the weekly increase.
  • Step 2: Use the arithmetic sequence formula to determine the price for each week.
  • Step 3: Match the calculated sequence to the provided options to find the correct one.

Now, let's work through these steps:

Step 1: The shirt starts at a price of 20.Eachweek,thepriceincreasesby20. Each week, the price increases by 5.

Step 2: Using the arithmetic sequence formula: an=a1+(n1)d a_n = a_1 + (n-1) \cdot d . - Week 0 (initial purchase): a1=20 a_1 = 20 - Week 1: a2=20+15=25 a_2 = 20 + 1 \cdot 5 = 25 - Week 2: a3=20+25=30 a_3 = 20 + 2 \cdot 5 = 30 - Week 3: a4=20+35=35 a_4 = 20 + 3 \cdot 5 = 35

Step 3: The calculated sequence is 20, 25, 30, 35, which needs to be reversed to match how sequences are usually listed.

The sequence in decreasing order is: 35,30,25,20 35, 30, 25, 20 .

This sequence matches choice 4, which is: 35, 30, 25, 20.

Therefore, the appropriate sequence to represent the price of the shirt is 35,30,25,20 35, 30, 25, 20 .

Answer

35 , 30 , 25 , 20