**Que:**Mandy sold 600 apples in 10 days. If the number of apples she sold increased by 4 each day, how many apples did she sell on the \(10^{th}\) day?

A. 36

B. 42

C. 60

D. 78

E. 100

- [email protected] Revolution
- Elite Legendary Member
**Posts:**3950**Joined:**24 Jul 2015**Location:**Las Vegas, USA**Thanked**: 19 times**Followed by:**36 members

00:00

**A**

**B**

**C**

**D**

**E**

A. 36

B. 42

C. 60

D. 78

E. 100

Score an excellent Q49-51 just like 70% of our students.

[Free] Full on-demand course (7 days) - 100 hours of video lessons, 490 lesson topics, and 2,000 questions.

[Course] Starting

Email to : [email protected]

- [email protected] Revolution
- Elite Legendary Member
**Posts:**3950**Joined:**24 Jul 2015**Location:**Las Vegas, USA**Thanked**: 19 times**Followed by:**36 members

Given: Mandy sold 600 apples in 10 days and the number of apples she sold increased by 4 each day

\(1^{st}\) day: x

\(2^{nd}\) day: x + 4

\(3^{rd}\) day: x + 4 + 4 = x + 2 * 4 .

.

.

\(10^{th}\) day: x + 9 * 4

=> x + (x + 4) + (x + 2 * 4) + ….+(x + 9 * 4) = 600

=> 10 x + 4 + 2 * 4 + …..+ 9 * 4 = 600

=> 10x + 4( 1 + 2 + …. + 9) = 600

=> 1 + 2 + 3 + 4 +…..+ n = \(\frac{n\left(n+1\right)}{2}\)

=> 10x + 4[\(\frac{9\cdot10}{2}\)] = 600

=> 10x + 180 = 600

=> 10x = 420

=> x = 42

=> ∴ \(10^{th}\) day = x + 9*4 = 42 + 36 = 78

Answer D

Score an excellent Q49-51 just like 70% of our students.

[Free] Full on-demand course (7 days) - 100 hours of video lessons, 490 lesson topics, and 2,000 questions.

[Course] Starting

Email to : [email protected]