Question Number 183457 by Acem last updated on 26/Dec/22
$${He}\:{went}\:{to}\:{work}\:{by}\:{his}\:{car}\:{at}\:{speed}\:\mathrm{120}\:{km}/{hr} \\ $$$$\:{and}\:{back}\:{home}\:{the}\:{same}\:{way}\:\mathrm{90}\:{km}/{hr},\:{find}\:{the} \\ $$$$\:{average}\:{speed}\:{for}\:{the}\:{entire}\:{distance}\:{traveled}. \\ $$$$ \\ $$
Answered by Matica last updated on 26/Dec/22
$$ \\ $$
Commented by Matica last updated on 26/Dec/22
Commented by Acem last updated on 26/Dec/22
$${Thx}\:{Mr}!\:{correct},\:{and}\:{it}'{s}\:{better}\:{rounded}\:{it}\:{to}\:{close} \\ $$$$\:{number}\:{such}\:\mathrm{102}.\mathrm{857}\:{is}\:{closer}\:{to}\:\mathrm{103}.\:{Thank}\:{you} \\ $$
Answered by mr W last updated on 26/Dec/22
$${v}_{{total}} =\frac{\mathrm{2}{d}}{\frac{{d}}{{v}_{\mathrm{1}} }+\frac{{d}}{{v}_{\mathrm{2}} }}=\frac{\mathrm{2}{v}_{\mathrm{1}} {v}_{\mathrm{2}} }{{v}_{\mathrm{1}} +{v}_{\mathrm{2}} } \\ $$$$\:\:\:\:\:\:\:\:\:=\frac{\mathrm{2}×\mathrm{120}×\mathrm{90}}{\mathrm{120}+\mathrm{90}}\approx\mathrm{103}\:{km}/{h} \\ $$
Commented by Acem last updated on 26/Dec/22
$${Thanks}\:{Mr}! \\ $$