Solve the problem.

A lab orders a shipment of frogs each week. Prices for the weekly shipments of frogs follow the distribution below:
\begin{tabular}{|c|c|c|c|}
\hline Price & $\$ 9.00$ & $\$$ & $\$$ \\
& & 11.00 & 15.00 \\
\hline Probability & 0.15 & 0.45 & 0.40 \\
\hline
\end{tabular}

Using this probability model to create a budget for the future, how much should the lab expect the shipments to cost per week?

Answer

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Answer

Therefore, the lab should expect the shipments to cost $\boxed{12.30}$ per week.

Steps

Step 1 ：Calculate the expected cost per week using the formula: $E = x_1 \cdot p_1 + x_2 \cdot p_2 + x_3 \cdot p_3$

Step 2 ：Substitute the given values: $E = 9.00 \cdot 0.15 + 11.00 \cdot 0.45 + 15.00 \cdot 0.40$

Step 3 ：Calculate the expression: $E = 1.35 + 4.95 + 6.00$

Step 4 ：Simplify the expression: $E = 12.30$

Step 5 ：Therefore, the lab should expect the shipments to cost $\boxed{12.30}$ per week.