Question: II. What I Know (Pretest)
1. $\frac{1}{2} + \frac{1}{3} = \underline{\hspace{1cm}}$
2. $\frac{3}{4} - \frac{1}{2} = \underline{\hspace{1cm}}$
3. $\frac{2}{3} \times \frac{3}{5} = \underline{\hspace{1cm}}$
4. $\frac{4}{5} \div \frac{2}{5} = \underline{\hspace{1cm}}$
5. $-8 + 11 = \underline{\hspace{1cm}}$
6. $-9 - (-6) = \underline{\hspace{1cm}}$
7. $-3 \times \frac{1}{2} = \underline{\hspace{1cm}}$
8. $\frac{5}{6} + \frac{1}{6} = \underline{\hspace{1cm}}$
9. $\frac{7}{8} \div \frac{7}{4} = \underline{\hspace{1cm}}$
10. Which operation uses Keep-Change-Flip?
1. **Problem:** Calculate $\frac{1}{2} + \frac{1}{3}$.
**Step 1:** Find a common denominator. The least common denominator (LCD) of 2 and 3 is 6.
**Step 2:** Convert fractions:
$$\frac{1}{2} = \frac{3}{6}, \quad \frac{1}{3} = \frac{2}{6}$$
**Step 3:** Add numerators:
$$\frac{3}{6} + \frac{2}{6} = \frac{3+2}{6} = \frac{5}{6}$$
**Answer:** $\frac{5}{6}$
2. **Problem:** Calculate $\frac{3}{4} - \frac{1}{2}$.
**Step 1:** LCD of 4 and 2 is 4.
**Step 2:** Convert fractions:
$$\frac{3}{4} = \frac{3}{4}, \quad \frac{1}{2} = \frac{2}{4}$$
**Step 3:** Subtract numerators:
$$\frac{3}{4} - \frac{2}{4} = \frac{3-2}{4} = \frac{1}{4}$$
**Answer:** $\frac{1}{4}$
3. **Problem:** Calculate $\frac{2}{3} \times \frac{3}{5}$.
**Step 1:** Multiply numerators and denominators:
$$\frac{2}{3} \times \frac{3}{5} = \frac{2 \times 3}{3 \times 5} = \frac{6}{15}$$
**Step 2:** Simplify fraction by dividing numerator and denominator by 3:
$$\frac{\cancel{6}^{2}}{\cancel{15}^{5}} = \frac{2}{5}$$
**Answer:** $\frac{2}{5}$
4. **Problem:** Calculate $\frac{4}{5} \div \frac{2}{5}$.
**Step 1:** Division of fractions uses Keep-Change-Flip:
$$\frac{4}{5} \div \frac{2}{5} = \frac{4}{5} \times \frac{5}{2}$$
**Step 2:** Multiply numerators and denominators:
$$\frac{4 \times 5}{5 \times 2} = \frac{20}{10}$$
**Step 3:** Simplify fraction by dividing numerator and denominator by 10:
$$\frac{\cancel{20}^{2}}{\cancel{10}^{1}} = 2$$
**Answer:** $2$
5. **Problem:** Calculate $-8 + 11$.
**Step 1:** Add integers:
$$-8 + 11 = 3$$
**Answer:** $3$
6. **Problem:** Calculate $-9 - (-6)$.
**Step 1:** Subtracting a negative is adding positive:
$$-9 - (-6) = -9 + 6$$
**Step 2:** Add integers:
$$-9 + 6 = -3$$
**Answer:** $-3$
7. **Problem:** Calculate $-3 \times \frac{1}{2}$.
**Step 1:** Multiply numerator and denominator:
$$-3 \times \frac{1}{2} = \frac{-3 \times 1}{2} = \frac{-3}{2}$$
**Answer:** $-\frac{3}{2}$
8. **Problem:** Calculate $\frac{5}{6} + \frac{1}{6}$.
**Step 1:** Same denominator, add numerators:
$$\frac{5}{6} + \frac{1}{6} = \frac{5+1}{6} = \frac{6}{6} = 1$$
**Answer:** $1$
9. **Problem:** Calculate $\frac{7}{8} \div \frac{7}{4}$.
**Step 1:** Use Keep-Change-Flip:
$$\frac{7}{8} \div \frac{7}{4} = \frac{7}{8} \times \frac{4}{7}$$
**Step 2:** Multiply numerators and denominators:
$$\frac{7 \times 4}{8 \times 7} = \frac{28}{56}$$
**Step 3:** Simplify by dividing numerator and denominator by 28:
$$\frac{\cancel{28}^{1}}{\cancel{56}^{2}} = \frac{1}{2}$$
**Answer:** $\frac{1}{2}$
10. **Question:** Which operation uses Keep-Change-Flip?
**Answer:** Division of fractions uses Keep-Change-Flip.