To evaluate \(\frac{1}{2} abcd\) given \(a = -2.4\), \(b = -\frac{5}{6}\), \(c = -1 \frac{1}{5}\), and \(d = \frac{2}{3}\), let's go step by step:
Step 1: Convert the Mixed Number
Convert \(c = -1 \frac{1}{5}\) to an improper fraction:
\[
-1 \frac{1}{5} = -\left(1 \times 5 + 1\right) / 5 = -\frac{6}{5}
\]
Step 2: Calculate \(abcd\)
Now substitute the values:
\[
abcd = a \cdot b \cdot c \cdot d = \left(-2.4\right) \cdot \left(-\frac{5}{6}\right) \cdot \left(-\frac{6}{5}\right) \cdot \left(\frac{2}{3}\right)
\]
Step 3: Break it down into parts
-
Calculate \(ab\):
\[
ab = (-2.4) \cdot \left(-\frac{5}{6}\right) = 2.4 \cdot \frac{5}{6}
\]
To compute this:
\[
ab = \frac{2.4 \cdot 5}{6} = \frac{12}{6} = 2
\]
-
Calculate \(cd\):
\[
cd = \left(-\frac{6}{5}\right) \cdot \left(\frac{2}{3}\right) = -\frac{6 \cdot 2}{5 \cdot 3} = -\frac{12}{15} = -\frac{4}{5} \quad (\text{after simplification})
\]
-
Combine \(ab\) and \(cd\):
\[
abcd = 2 \cdot \left(-\frac{4}{5}\right) = -\frac{8}{5}
\]
Step 4: Calculate \(\frac{1}{2} abcd\)
Now we compute:
\[
\frac{1}{2} abcd = \frac{1}{2} \cdot \left(-\frac{8}{5}\right) = -\frac{8}{10} = -\frac{4}{5}
\]
Thus, the value of \(\frac{1}{2} abcd\) when \(a = -2.4\), \(b = -\frac{5}{6}\), \(c = -1 \frac{1}{5}\), and \(d = \frac{2}{3}\) is \(-\frac{4}{5}\).