Work out \( \left(7.3 \times 10^{5}\right)+\left(4 \times 10^{5}\right) \) Give your answer in standard index form.

To work out \( \left(7.3 \times 10^{5}\right)+\left(4 \times 10^{5}\right) \), notice that both terms have the same power of ten. You can simply add the coefficients: \[ 7.3 + 4 = 11.3 \] Now, combine this with the \(10^{5}\): \[ 11.3 \times 10^{5} \] To express it in standard index form, since \(11.3\) can be written as \(1.13 \times 10^{1}\), we can rewrite it: \[ 1.13 \times 10^{1} \times 10^{5} = 1.13 \times 10^{6} \] So, the answer in standard index form is: \[ 1.13 \times 10^{6} \]