Question

ramam saved Rs 5 in the first week of a year and then increased his weekly saving by Rs 1.75 . if in the nth week, his weekly saving become Rs 20.75 , find n.​

Answer 1

Given :–

• Raman shaved Rs. 5 in the first week of a year.
• Increased his weekly savindhan by Rs. 1.75 in the nth week.
• His weekly shaving becomes Rs. 20.75.

To Find :–

• Value of n.

Solution :–

• Shaving in the first week = Rs. 5

According to the question,

Increased Rs. 1.75.

• In the second week = 5 + 1.75 = Rs. 6.75

• In the third week = 6.75 + 1.75 = Rs. 8.50

Now, the series is 5, 6.75, 8.50.......

This is an A.P. because it's common difference is same.

Common difference = a₃ – a₂ = a₂ – a₁

• a₃ = 8.50
• a₂ = 6.75
• a₁ = 5

So,

⟹ 8.50 – 6.75 = 6.75 – 5

⟹ 1.75 = 1.75

• Common difference (d) = 1.75

Given that,

In the nth week, her saving becomes Rs. 20.75.

So,

• $a_{n}$ = 20.75

Formula Used :–

• $a_{n}$ = a + (n – 1)d

Here,

• a = 5
• d = 1.75

Now, put these value in the formula.

⟹ 20.75 = 5 + (n – 1)(1.75)

⟹ 20.75 – 5 = (n – 1)(1.75)

⟹ 15.75 = (n – 1)(1.75)

⟹ $\dfrac{15.75}{1.75}$ = n – 1

⟹ $\dfrac{1575\cancel0}{175\cancel0}$ = n – 1

⟹ $\dfrac{\cancel{1575}}{\cancel{175}}$ = n – 1

⟹ $\dfrac{\cancel{315}}{\cancel{35}}$ = n – 1

⟹ $\dfrac{\cancel{63}}{\cancel{7}}$ = n – 1

⟹ 9 = n – 1

⟹ 9 + 1 = n

⟹ 10 = n

Hence,

The value of n is 10.

Means, in the 10th week, his weekly shaving is Rs. 20.75.

Answer 2

Answer:

you see in picture

Step-by-step explanation:

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