Question

On 1st November Priya has 200 sweets in a box. She eats no sweets first day and she eats 8 sweets per day from the box thereafter. On what day of the month will she have 40 sweets left? Show your calculations using the formula for Tn of an arithmetic sequence.

Answer 1

She will have 40 sweets left on 21st of November.

Step-by-step explanation:

On 1st November Priya has 200 sweets in a box. She eats no sweets first day and she eats 8 sweets per day from the box thereafter.

Day 1 = 200 sweets

Day 2 = 192 sweets (Ate 8 sweets)

Day 3 = 184 sweets

Day n = 40 sweets.

Here 200, 192, 184,.............,40 is an arithmetic sequence.

Here 1st term = a = 200

Common difference = d = 192 - 200 = -8

nth term = $a_{n} = 40$

=> a + (n-1)d = 40

=> 200 + (n -1) x (-8) = 40

=> 200 - 8n + 8 = 40

=> 208 - 8n = 40

=> 8n = 208 - 40 = 168

=> n = $\frac{168}{8}$ = 21

Hence, She will have 40 sweets left on 21st of November.

Answer 2

Answer40 :

Step-by-step explanation: