A sports shop had 400 tennis balls for sale. Each tennis ball is sold at $3. At the end of each day, the number of tennis balls sold was recorded in the bar graph shown.

1. What fraction of the total number of tennis balls was left at the end of Day 4? Express your answer in its simplest form.
2. If the shop decided to sell every 4 tennis balls at $10 from Day 5 onwards, how much less would it collect from the sale of the tennis balls?

(a)
Number of tennis balls left at the end of Day 4
= 400 - 44 - 76 - 40 - 76
= 164

Fraction of tennis balls left at the end of Day 4
= ¹⁶⁴₄₀₀
= ⁴¹₁₀₀

(b)
Number of tennis balls sold from Day 5 to Day 6
= 44 + 64
= 108

Amount that it would collect if it sold the 108 tennis balls at the original price
= 108 x 3
= $324

Number of sets of 4 tennis balls
= 108 ÷ 4
= 27

Amount that it would collect if it sold the 108 tennis balls at every 4 tennis balls at $10
= 27 x 10
= $270

Amount that it would collect less  from the sale of the tennis balls
= 324 - 270
= $54

Answer(s): (a) ⁴¹₁₀₀; (b) $54