Question

a) A child makes a pattern with blocks on the floor. She puts 55 blocks in the first
row, 50 in the second, 45 in the third and so on.
i- Write down an expression for the number of blocks in the nth row.
ii- Determine the number of blocks in the 7th row.
Determine the total number of blocks in the first five rows.
iv- How many rows can she have in her pattern if she has 300 blocks to play
with?

Answer 1

Answer:

i-Answer: 15 blocks.

ii-Answer:25 blocks.

ii-Answer:60

Hope it will help you but it's right

Mark as brainilest please

Answer 2

i- The number of blocks in the nth row is a+(n-1)×d.

ii- The number of blocks in the 7th row is 25.

iii- The total number of blocks in the 5th row is 225.

iv. She can have eight rows if she has 300 blocks.

Given,

A child makes a pattern with blocks on the floor. She puts 55 blocks in the first row, 50 in the second, 45 in the third, and so on.

To Find,

Answers to the given questions.

Solution,

i. An expression for the number of blocks in the nth row is :

Let the number of blocks in the nth row be n.

The first term = a

Common difference = d

So, nth term = a+(n-1)×d.

ii. The number of blocks in the 7th row is:

Using the above expression, nth term = a+(n-1)×d.

n = 7 , a = 55 and d = 50 - 55 = -5

= 55+(7-1)×(-5)

= 55 + (6)×(-5)

= 55 - 30

= 25.

iii.  The total number of blocks in the first five rows are:

So, the series is decreasing by 5

1st row = 55

2nd row = 50

3rd row = 45

4th row = 40

5th row = 35

The total number of blocks in the first five rows are :

= 55+50+45+40+35

= 225.

iv. Let's have a sum of the blocks of all the rows till 300

= 55+50+45+40+35+30+25+20

=300

So, the number of rows is 8.

i- The number of blocks in the nth row is a+(n-1)×d.

ii- The number of blocks in the 7th row is 25.

iii- The total number of blocks in the 5th row is 225.

iv. She can have eight rows if she has 300 blocks.

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