Grade 10 Computing, Week 10, Lesson 18: Practical lesson

Practice and chapter test

Lessons 18–19 · 2 lessons · N. I. Taylaqov (general editor), A. B. Akhmedov, M. D. Pardayeva, A. A. Abdug‘aniyev, U. M. Mirsanov. Informatics and Information Technologies, Grade 10, 1st edition. “Extremum-Press”, Tashkent, 2017

Practical lesson

Textbook: p. 41

GoalBuilds budget, unit-conversion and quadratic-equation tables; calculates a percentage share and protects a formula from errors with IF.

New words

percentage share: part ÷ whole · 100 · foiz ulushiunit conversion: recalculating a quantity from one unit to another · birlikni almashtirisherror protection: an IF that avoids a formula that would give an error · xatodan himoyapie chart: shows the shares of parts in a whole · pie diagrammasi

Explanation

In this practical lesson the formulas of the chapter are used in three small projects. The first is a table of monthly expenses: SUM, AVERAGE, MAX, MIN and the share of each month in the total, =B2/$B$8*100 (percent), are calculated. The second is the conversion of speed units: to go from km/h to m/s multiply by 1000/3600. The third is a quadratic “calculator” where a, b and c are entered: D is calculated and the roots appear only when D ≥ 0, otherwise “ildiz yo‘q” (no root) is written. In each table colour the input cells (for example yellow) so the user knows which cells may be changed. Do not enter personal data (phone, address) into the finished table.

Worked examples

Club expenses (so‘m): Jan. 120 000, Feb. 95 000, Mar. 140 000, Apr. 110 000, May 130 000, Jun. 105 000. Total (B8) = 700 000; mean ≈ 116 667; the largest is March (140 000). The share of March is =140000/700000*100 = 20%.

Speed: A2:A5 hold 36, 54, 72, 90 km/h; B2 = A2*1000/3600 → 10, 15, 20, 25 m/s. Quadratic: D1 = B1^2-4*A1*C1; root: =IF(D1>=0,(-B1+SQRT(D1))/(2*A1),"ildiz yo‘q"). With a = 1, b = –5, c = 6, D = 1 and the root is 3; with a = 1, b = 2, c = 5, D = –16 and the result is “ildiz yo‘q”.

Class activity

“The three-cell calculator”: pairs add one more column to the speed table – the distance covered in an hour; one pair marks the input cells yellow and another tests the table.

Practice

The total expense is 700 000 and March costs 140 000 so‘m. What percent is the share of March?

How many m/s is 72 km/h?

What is D when a = 1, b = 2, c = 5?

Why is the root formula put inside IF(D>=0, …)?