Can anyone help me with this question

Baby Pty Ltd. is planning to launch a new brand of makeup product. Based on market research, if sales are high they can make a profit of $3.4 million per year. If sales are 'so so' they can make a profit of $1.6 million per year. Finally, if sales are low they can lose $0.5 million. The probabilities for the two profit scenarios are 0.64 and 0.13, respectively. Calculate the standard deviation of profit for the product (in $ millions) to 3 decimal places.

Thank you!!!